TclX(TCL)

NAME
TclX - Extended Tcl: Extended command set for Tcl

INTRODUCTION

This man page contains the documentation for all of the extensions that are added to Tcl 7.0 by Extended Tcl (TclX 7.0a). These extensions provide extend Tcl's capabilities by adding new commands to it, without changing the syntax of standard Tcl. Extended Tcl is a superset of standard Tcl and is built alongside the standard Tcl sources. Extended Tcl has three basic functional areas: A set of new commands, a Tcl shell (i.e. a Unix shell-style command line and interactive environment), and a user-extensible library of useful Tcl procedures, any of which can be automatically loaded on the first attempt to execute it.

The command descriptions are separated into several sections:

    o General Commands

    o Debugging and Development Commands

    o Unix Access Commands

    o File I/O Commands

    o TCP/IP Server Access

    o File Scanning Commands

    o Math Commands

    o List Maninipulation Commands

    o Keyed Lists

    o String and Character Manipulation Commands

    o XPG/3 Message Catalog Commands

    o Extended Tcl Shell

    o Help Facility

    o Tcl Loadable Libraries and Packages

GENERAL COMMANDS

A set of general, useful Tcl commands, includes a command to begin an interactive session with Tcl, a facility for tracing execution, and a looping command.

dirs
    This procedure lists the directories in the directory stack.

commandloop ?prompt1? ?prompt2?
    Create an interactive command loop for the current TCL interpreter. This command receives commands from stdin and executes them. It is useful TCL scripts that do not normally converse interactively with a user through a Tcl command interpreter, but which sometimes want to enter this mode.

    Prompt1 is a Tcl command that is evaluated to output a prompt string. The old value of tcl_prompt1 is saved and it is set to this value for the duration of the command loop. Prompt2 is a command that is evaluated to output the ``downlevel prompt'', which is the prompt which is issued for continuation input. The old value of tcl_prompt2 is saved and it is set to this value for the duration of the command loop.

    When the command terminates, the variables for the prompt hooks will be set to their old value. If these arguments are not specified, the prompt hooks use their current value.

echo ?str ...?
    Writes zero or more strings to standard output, followed by a newline.

infox option
    Return information about Extended Tcl, or the current application. The following infox command options are available:

    version
        Return the version number of Extended Tcl. The version number for Extended Tcl is generated by combining the base version of the standard Tcl code with a letter indicating the version of Extended Tcl being used. This is the documentation for version 7.0a.

    patchlevel
        Return the patchlevel for Extended Tcl.

    have_flock
        Return 1 if the flock command defined, 0 if it is not available.

    have_fsync
        Return 1 if the fsync system call is available and the sync command will sync individual files. 0 if it is not available and the sync command will always sync all file buffers.

    have_msgcats
        Return 1 if XPG message catalogs are available, 0 if they are not. The catgets is designed to continue to function without message catalogs, always returning the default string.

    have_posix_signals
        Return 1 if Posix signals are available (block and unblock options available for the signal command). 0 is returned if Posix signals are not available.

    have_sockets
        Return 1 if sockets are available (server_open and server_info commands and fstat removehost option). 0 is returned if sockets are not available.

    appname
        Return the symbolic application name of the current application linked with the Extended Tcl library. The C variable tclAppName must be set by the application to return an application specific value for this variable.

    applongname
        Return a natural language name for the current application. The C variable tclLongAppName must be set by the application to return an application specific value for this variable.

    appversion
        Return the version number for the current application. The C variable tclAppVersion must be set by the application to return an application-specific value for this variable.

    apppatchlevel
        Return the patchlevel for the current application. The C variable tclAppPatchlevel must be set by the application to return an application-specific value for this variable.

for_array_keys var array_name code
    This procedure performs a foreach-style loop for each key in the named array. The break and continue statements work as with foreach.

for_recursive_glob var dirlist globlist code
    This procedure performs a foreach-style loop over recursively matched files. All directories in dirlist are recursively searched (breadth-first), comparing each file found against the file glob patterns in globlist. For each matched file, the variable var is set to the file path and code is evaluated. Symbolic links are not followed.

loop var first limit ?increment? body
    Loop is a looping command, similar in behavior to the Tcl for statement, except that the loop statement achieves substantially higher performance and is easier to code when the beginning and ending values of a loop are known, and the loop variable is to be incremented by a known, fixed amount every time through the loop.

     The var argument is the name of a Tcl variable that will contain the loop index. The loop index is set to the value specified by first. The Tcl interpreter is invoked upon body zero or more times, where var is incremented by increment every time through the loop, or by one if increment is not specified. Increment can be negative in which case the loop will count downwards.

    When var reaches limit, the loop terminates without a subsequent execution of body. For instance, if the original loop parameters would cause loop to terminate, say first was one, limit was zero and increment was not specified or was non-negative, body is not executed at all and loop returns.

    The first, limit and increment are integer expressions. They are only evaulated once at the beginning of the loop.

    If a continue command is invoked within body then any remaining commands in the current execution of body are skipped, as in the for command. If a break command is invoked within body then the loop command will return immediately. Loop returns an empty string.

popd
    This procedure pops the top directory entry from the directory stack and make it the current directory.

pushd ?dir?
    This procedure pushs the current directory onto the directory stack and cd to the specified directory. If the directory is not specified, then the current directory is pushed, but remains unchanged.

recursive_glob dirlist globlist
    This procedure returns a list of recursively matches files. All directories in dirlist are recursively searched (breadth-first), comparing each file found against the file glob patterns in globlist. Symbolic links are not followed.

showproc ?procname ...?
    This procedure lists the definition of the named procedures. Loading them if it is not already loaded. If no procedure names are supplied, the definitions of all currently loaded procedures are returned.

DEBUGGING AND DEVELOPMENT COMMANDS
This section contains information on commands and procdures that are
    useful for developing and debugging Tcl scripts.

cmdtrace level|on ?noeval? ?notruncate? ?procs? ?fileid?
    Print a trace statement for all commands executed at depth of level or below (1 is the top level). If on is specified, all commands at any level are traced. The following options are available:

    noeval
        Causes arguments to be printed unevaluated. If noeval is specified, the arguments are printed before evaluation. Otherwise, they are printed afterwards.

        If the command line is longer than 60 characters, it is truncated to 60 and a "..." is postpended to indicate that there was more output than was displayed. If an evaluated argument contains a space, the entire argument will be enclosed inside of braces (`{}') to allow the reader to visually separate the arguments from each other.

    notruncate
        Disables the truncation of commands and evaluated arguments.

    procs
        Enables the tracing of procedure calls only. Commands that aren't procedure calls (i.e. calls to commands that are written in C, C++ or some object-compatible language) are not traced if the procs option is specified. This option is particularly useful for greatly reducing the output of cmdtrace while debugging.

    fileid
        This is a file id as returned by the open command. If specified, then the trace output will be written to the file rather than stdout. A stdio buffer flush is done after every line is written so that the trace may be monitored externally or provide useful information for debugging problems that cause core dumps.
The most common use of this command is to enable tracing to a file during the development. If a failure occurs, a trace is then available when needed. Command tracing will slow down the execution of code, so it should be removed when code is debugged. The following command will enable tracing to a file for the remainder of the program:

      cmdtrace on [open cmd.log w]

cmdtrace off
    Turn off all tracing.

cmdtrace depth
    Returns the current maximum trace level, or zero if trace is disabled.

edprocs ?proc...?
    This procedure writes the named procedures, or all currently defined procedures, to a temporary file, then calls an editor on it (as specified by the EDITOR environment variable, or vi if none is specified), then sources the file back in if it was changed.

profile ?-commands? on
    profile off arrayVar
    This command is used to collect a performance profile of a Tcl script. It collects data at the Tcl procedure level. The number of calls to a procedure, and the amount of real and CPU time is collected. Time is also collected for the global context. The procedure data is collected by bucketing it based on the procedure call stack, this allows determination of how much time is spent in a particular procedure in each of it's calling contexts.

    The on option enables profile data collection. If the -commands option is specifed, data on all commands within a procedure is collected as well a procedures. Multiple occurrences of a command within a procedure are not distinguished, but this data may still be useful for analysis.

    The off option turns off profiling and moves the data collected to the array arrayVar. The array is address by a list containing the procedure call stack. Element zero is the top of the stack, the procedure that the data is for. The data in each entry is a list consisting of the procedure call count and the real time and CPU time in milliseconds spent in the procedure (and all procedures it called). The list is in the form {count real cpu}. A Tcl procedure profrep is supplied for reducing the data and producing a report

profrep profDataVar sortKey ?outFile? ?userTitle?
    This procedure generates a report from data collect from the profile command. ProfDataVar is the name of the array containing the data returned by the profile command. SortKey indicates which data value to sort by. It should be one of "calls", "cpu" or "real". OutFile is the name of file to write the report to. If omitted, stdout is assumed. UserTitle is an optional title line to add to output.

saveprocs fileName ?proc...?
    This prodcure saves the definition of the named procedure, or all currently defined procedures if none is specified, to the named file.

UNIX ACCESS COMMANDS

These commands provide access to many basic Unix facilities, including process handling, date and time processing, signal handling, linking and unlinking files, setting file, process, and user attributes, and the executing commands via the shell.

alarm seconds
    Instructs the system to send a SIGALRM signal in the specified number of seconds. This is a floating point number, so fractions of a section may be specified. If seconds is 0.0, any previous alarm request is canceled. Only one alarm at a time may be active; the command returns the number of seconds left in the previous alarm. On systems without the setitimer system call, seconds is rounded up to an even number of seconds.

chgrp group filelist
    Set the group id of each file in the list filelist to group, which can be either a group name or a numeric group id.

chmod mode filelist
    Set permissions of each of the files in the list filelist to mode, where mode is an absolute numeric mode or symbolic permissions as in the UNIX chmod(1) command. To specify a mode as octal, it should be prefixed with a "0" (e.g. 0622).

chown owner|{owner group} filelist
    Set owner of each file in the list filelist to owner, which can be a user name or numeric user id. If the first parameter is a list, then the owner is set to the first element of the list and the group is set to the second element. Group can be a group name or numeric group id. If group is {}, then the file group will be set to the login group of the specified user.

convertclock dateString ?GMT|{}? ?baseClock?
    Convert dateString to an integer clock value (see getclock). This command can parse and convert virtually any standard date and/or time string, which can include standard time zone mnemonics. If only a time is specified, the current date is assumed. If the string does not contain a time zone mnemonic, the local time zone is assumed, unless the GMT argument is specified, in which case the clock value is calculated assuming that the specified time is relative to Greenwich Mean Time. If baseClock is specified, it is taken as the current clock value. This is useful for determining the time on a specific day.

    The character string consists of zero or more specifications of the following form:

    time - A time of day, which is of the form hh[:mm[:ss]] [meridian] [zone] or hhmm [meridian] [zone]. If no meridian is specified, hh is interpreted on a 24-hour clock.

    date - A specific month and day with optional year. The acceptable formats are mm/dd[/yy], yyyy/mm/dd, monthname dd[, yy], dd monthname [yy], and day, dd monthname yy. The default year is the current year. If the year is less then 100, then 1900 is added to it.

    relative time - A specification relative to the current time. The format is number unit; acceptable units are year, fortnight, month, week, day, hour, minute (or min), and second (or sec). The unit can be specified as a singular or plural, as in 3 weeks. These modifiers may also be specified: tomorrow, yesterday, today, now, last, this, next, ago.

    The actual date is calculated according to the following steps. First, any absolute date and/or time is processed and converted. Using that time as the base, day-of-week specifications are added. Next, relative specifications are used. If a date or day is specified, and no absolute or relative time is given, midnight is used. Finally, a correction is applied so that the correct hour of the day is produced after allowing for daylight savings time differences.

    convertclock ignores case when parsing all words. The names of the months and days of the week can be abbreviated to their first three letters, with optional trailing period. Periods are ignored in any timezone or meridian values.

    Note that convertclock will convert symbolic time-zone names, but these are not standardized and there are conflicts with various parts of the world. Use GMT when trying to produce a portable time that can then be converted back to a numeric value.

    The only dates in the range 1902 and 2037 may be converted. Some examples are:

        convertclock "14 Feb 92"
        convertclock "Feb 14, 1992 12:20 PM PST"
        convertclock "12:20 PM Feb 14, 1992"

execl ?-argv0 argv0? prog ?arglist?
    Do an execl, replacing the current program (either Extended Tcl or an application with Extended Tcl embedded into it) with prog and passing the arguments in the list arglist.

    The -argv0 options specifies that argv0 is to be passed to the program as argv [0] rather than prog.

    Note: If you are using execl in a Tk application and it fails, you may not do anything that accesses the X server or you will receive a BadWindow error from the X server. This includes executing the Tk version of the exit command. We suggest using the following command to abort Tk applications after an execl failure:

        kill [id process]

fmtclock clockval ?format? ?GMT|{}?
    Converts a Unix integer time value, typically returned by getclock, convertclock, or the atime, mtime, or ctime options of the file command, to human-readable form. The format argument is a string that describes how the date and time are to be formatted. Field descriptors consist of a ``%'' followed by a field descriptor character. All other characters are copied into the result. Valid field descriptors are:

        %% - Insert a %.
        %a - Abbreviated weekday name.
        %A - Full weekday name
        %b - Abbreviated month name.
        %B - Full month name.
        %d - Day of month (01 - 31).
        %D - Date as %m/%d/%y.
        %e - Day of month (1-31), no leading zeros.
        %h - Abbreviated month name.
        %H - Hour (00 - 23).
        %I - Hour (00 - 12).
        %j - Day number of year (001 - 366).
        %m - Month number (01 - 12).
        %M - Minute (00 - 59).
        %n - Insert a new line.
        %p - AM or PM.
        %r - Time as %I:%M:%S %p.
        %R - Time as %H:%M.
        %S - Seconds (00 - 59).
        %t - Insert a tab.
        %T - Time as %H:%M:%S.
        %U - Week number of year (01 - 52), Sunday is the first
             day of the week.
        %w - Weekday number (Sunday = 0).
        %W - Week number of year (01 - 52), Monday is the first
             day of the week.
        %x - Local specific date format.
        %X - Local specific time format.
        %y - Year within century (00 - 99).
        %Y - Year as ccyy (e.g. 1990)
        %Z - Time zone name.

    If format is not specified, "%a %b %d %H:%M:%S %Z %Y" is used. If GMT is specified, the time will be formated as Greenwich Mean Time. If the argument is not specified or is empty, then the local timezone will be used as defined by the TIMEZONE environment variable.

chroot dirname
    Change root directory to dirname, by invoking the POSIX chroot(2) system call. This command only succeeds if running as root.

fork
    Fork the current Tcl process. Fork returns zero to the child process and the process number of the child to the parent process. If the fork fails, a Tcl error is generated.

    If an execl is not going to be performed before the child process does output, or if a close and dup sequence is going to be performed on stdout or stderr, then a flush should be issued against stdout, stderr and any other open output file before doing the fork. Otherwise characters from the parent process pending in the buffers will be output by both the parent and child processes.

    Note: If you are forking in a Tk based apllication you must execl before doing any window operations in the child or you will receive a BadWindow error from the X server.

getclock
    Return the current date and time as a system-dependent integer value. The unit of the value is seconds, allowing it to be used for relative time calculations.

id options
    This command provides a means of getting, setting and converting user, group and process ids. The id command has the following options:

    id user ?name?

    id userid ?uid?
        Set the real and effective user ID to name or uid, if the name (or uid) is valid and permissions allow it. If the name (or uid) is not specified, the current name (or uid) is returned.

    id convert userid uid

    id convert user name
        Convert a user ID number to a user name, or vice versa.

    id group ?name?

    id groupid ?gid?
        Set the real and effective group ID to name or gid, if the name (or gid) is valid and permissions allow it. If the group name (or gid) is not specified, the current group name (or gid) is returned.

    id convert groupid gid

    id convert group name
        Convert a group ID number to a group name, or vice versa.

    id effective user

    id effective userid
        Return the effective user name, or effective user ID number, respectively.

    id effective group

    id effective groupid
        Return the effective group name, or effective group ID number, respectively.

    id process
        Return the process ID of the current process.

    id process parent
        Return the process ID of the parent of the current process.

    id process group
        Return the process group ID of the current process.

    id process group set
        Set the process group ID of the current process to its process ID.

kill ?-pgroup ?signal? idlist
    Send a signal to the each process in the list idlist, if permitted. Signal, if present, is the signal number or the symbolic name of the signal, see the signal system call manual page. The leading ``SIG'' is optional when the signal is specified by its symbolic name. The default for signo is 15, SIGTERM.

    If -pgroup is specified, the numbers in idlist are take as process group ids and the signal is sent to all of the process in that process group. A process group id of 0 specifies the current process group.

link ?-sym? srcpath destpath
    Create a directory entry, destpath, linking it to the existing file, srcpath. If -sym is specified, a symbolic link, rather than a hard link, is created. (The -sym option is only available on systems that support symbolic links.)

mkdir ?-path? dirList
    Create each of the directories in the list dirList. The mode on the new directories is 777, modified by the umask. If -path is specified, then any non-existent parent directories in the specified path(s) are also created.

nice ?priorityincr?
    Change or return the process priority. If priorityincr is omitted, the current priority is returned. If priorityincr is positive, it is added to the current priority level, up to a system defined maximum (normally 19),

    Negative priorityincr values cumulatively increase the program's priority down to a system defined minimum (normally -19); increasing priority with negative niceness values will only work for the superuser.

    The new priority is returned.

readdir dirPath
    Returns a list containing the contents of the directory dirPath. The directory entries "." and ".." are not returned.

rmdir ?-nocomplain? dirList
    Remove each of the directories in the list dirList. If -nocomplain is specified, then errors will be ignored.

signal action siglist ?command?
    Specify the action to take when a Unix signal is received by Extended Tcl, or a program that embeds it. Siglist is a list of either the symbolic or numeric Unix signal (the SIG prefix is optional). Action is one of the following actions to be performed on receipt of the signal. To specify all modifiable signals, use `*' (this will not include SIGKILL and SIGSTOP, as they can not be modified).

    default - Perform system default action when signal is received (see signal system call documentation).

    ignore - Ignore the signal.

    error - Generate a catchable Tcl error. It will be as if the command that was running returned an error. The error code will be in the form:
        POSIX SIG signame
    For the death of child signal, signame will always be SIGCHLD, rather than SIGCLD, to allow writing portable code.

    trap - When the signal occurs, execute command and continue execution if an error is not returned by command. The command will be executed in the global context. The command will be edited before execution, replacing occurrences of "%S" with the signal name. Occurrences of "%%" result in a single "%". This editing occurs just before the trap command is evaluated. If an error is returned, then follow the standard Tcl error mechanism. Often command will just do an exit.

    get - Retrieve the current settings of the specified signals. A keyed list will be returned were the keys are one of the specified signals and the values are a list cosisting of the action associated with the signal, a 0 if the signal may be delivered (not block) and a 1 if it is blocked. The actions maybe one of `default',`ignore', `error' or `trap. If the action is trap, the third element is the command associated with the action. The action `unknown' is returned if a non-Tcl signal handler has been associated with the signal.

    set - Set signals from a keyed list in the format returned by the get. For this action, siglist is the keyed list of signal state. Signals with an action of `unknown' are not modified.

    block - Block the specified signals from being received. (Posix systems only).

    unblock - Allow the specified signal to be received. Pending signals will not occur. (Posix systems only).

    The signal action will remain enabled after the specified signal has occurred. The exception to this is SIGCHLD on systems without Posix signals. For these systems, SIGCHLD is not be automatically reenabled. After a SIGCHLD signal is received, a call to wait must be performed to retrieve the exit status of the child process before issuing another signal SIGCHLD ... command. For code that is to be portable between both types of systems, use this approach.

    Signals are not processed until after the completion of the Tcl command that is executing when the signal is received. If an interactive Tcl shell is running, then the SIGINT will be set to error, non-interactive Tcl sessions leave SIGINT unchanged from when the process started (normally default for foreground processes and ignore for processes in the background).

sleep seconds
    Sleep the Extended Tcl process for seconds seconds.

system command
    Executes command via the system(3) call. Differs from exec in that system doesn't return the executed command's standard output as the result string, and system goes through the Unix shell to provide wildcard expansion, redirection, etc, as is normal from an sh command line. The exit code of the command is returned.

sync ?fileId?
    If fileId is not specified, or if it is and this system does not support the fsync system call, issues a sync system call to flush all pending disk output. If fileId is specified and the system does support the fsync system call, issues an fsync on the file corresponding to the specified Tcl fileId to force all pending output to that file out to the disk.

    If fileId is specified, the file must be writable. A flush will be issued against the fileId before the sync.

    The infox have_fsync command can be used to determine if "sync fileId" will do a sync or a fsync.

times
    Return a list containing the process and child execution times in the form:
        utime stime cutime cstime
    Also see the times(2) system call manual page. The values are in milliseconds.

umask ?octalmask?
    Sets file-creation mode mask to the octal value of octalmask. If octalmask is omitted, the current mask is returned.

unlink ?-nocomplain? filelist
    Delete (unlink) the files whose names are in the list filelist. If -nocomplain is specified, then errors will be ignored.

wait ?-nohang? ?-untraced? ?-pgroup? ?pid?
    Waits for a process created with the execl command to terminate, either due to an untrapped signal or call to exit system call. If the process id pid is specified, they wait on that process, otherwise wait on any child process to terminate.

    If -nohang is specified, then don't block waiting on a process to terminate. If no process is immediately available, return an empty list. If -untraced is specified then the status of child processes that are stopped, and whose status has not yet been reported since they stopped, are also returned. If -pgroup is specfied and pid is not specified, then wait on any child process whose process groupd ID is they same as the calling process. If pid is specified with -pgroup, then it is take as a process group ID, waiting on any process in that process group to terminate.

    Wait returns a list containing three elements: The first element is the process id of the process that terminated. If the process exited normally, the second element is `EXIT', and the third contains the numeric exit code. If the process terminated due to a signal, the second element is `SIG', and the third contains the signal name. If the process is currently stopped (on systems that support SIGSTP), the second element is `STOP', followed by the signal name.

    Note that it is possible to wait on processes to terminate that were create in the background with the exec command. However, if any other exec command is executed after the process terminates, then the process status will be reaped by the exec command and will not be available to the wait command.

FILE I/O COMMANDS

These commands extend the stdio-style file I/O capabilities present in Tcl and above. These extensions include searching ASCII-sorted data files, copying files, duplicating file descriptors, control of file access options, retrieving open file status, and creating pipes with the pipe system call. An interface to the select system call is available on Unix systems that support it.

It should be noted that Tcl file I/O is implemented on top of the stdio library. By default, the file is buffered. When communicating to a process through a pipe, a flush command should be issued to force the data out. Alternatively, the fcntl command may be used to set the buffering mode of a file to line-buffered or unbuffered.

bsearch fileId key ?retvar? ?compare_proc?
    Search an opened file fileId containing lines of text sorted into ascending order for a match. Key contains the string to match. If retvar is specified, then the line from the file is returned in retvar, and the command returns 1 if key was found, and 0 if it wasn't. If retvar is not specified or is a null name, then the command returns the line that was found, or an empty string if key wasn't found.

    By default, the key is matched against the first white-space separated field in each line. The field is treated as an ASCII string. If compare_proc is specified, then it defines the name of a Tcl procedure to evaluate against each line read from the sorted file during the execution of the bsearch command. Compare_proc takes two arguments, the key and a line extracted from the file. The compare routine should return a number less than zero if the key is less than the line, zero if the key matches the line, or greater than zero if the key is greater than the line. The file must be sorted in ascending order according to the same criteria compare_proc uses to compare the key with the line, or errouenous results will occur.

copyfile ?-bytes num|-maxbytes num? fromFileId toFileId
    Copies the rest of the file specified by fromFileId, starting from its current position, to the file specified by toFileId, starting from its current position.

    If -bytes is specified, then num bytes are copied. If less than num bytes are available, an error is returned. If -maxbytes is specified, then num bytes are copied but no error is returned if less are available.

    The command returns the number of bytes that were copied.

    The -bytes option is particularly useful for mixing binary data in with ASCII commands or data in a data stream.

dup fileId ?targetFileId?
    Duplicate an open file. A new file id is opened that addresses the same file as fileId.

    If targetFileId is specified, the the file is dup to this specified file id. Normally this is stdin, stdout, or stderr. The dup command will handle flushing output and closing this file. The target file should be open if its one of stdin, stdout, or stderr and the process is not going to do an execl. Otherwise internal C code that uses one of these files via direct access to stdio FILE struct may behave strangely or fail.

fcntl fileId attribute ?value?
    This command either sets or clears a file option or returns its current value. If value are not specified, then the current value of attribute is returned. The following attributes may be specified:

    RDONLY - The file is opened for reading only. (Get only)

    WRONLY - The file is opened for writing only. (Get only)

    RDWR - The file is opened for reading and writing. (Get only)

    READ - If the file is readable. (Get only).

    WRITE - If the file is writable. (Get only).

    APPEND - The file is opened for append-only writes. All writes will be forced to the end of the file.

    NONBLOCK - The file is to be accessed with non-blocking I/O. See the read system call for a description of how it affects the behavior of file reads.

    CLOEXEC - Close the file on an process exec. If the execl command or some other mechanism causes the process to do an exec, the file will be closed if this option is set.

    NOBUF - The file is not buffered. If set, then there no stdio buffering for the file.

    LINEBUF - Output the file will be line buffered. The buffer will be flushed when a newline is written, when the buffer is full, or when input is requested.

    The APPEND, NONBLOCK, and CLOEXEC attributes may be set or cleared by specifying the attribute name and a value 1 to set the attribute and 0 to clear it.

    The NOBUF and LINEBUF attributes may only be set (a value of 1) and only one of the options may be selected. Once set, it may not be changed. These options should be set before any I/O operations have been done on the file or data may be lost.

flock options fileId ?start? ?length? ?origin?
    This command places a lock on all or part of the file specified by fileId. The lock is either advisory or mandatory, depending on the mode bits of the file. The lock is placed beginning at relative byte offset start for length bytes. If start or length is omitted or empty, zero is assumed. If length is zero, then the lock always extents to end of file, even if the file grows. If origin is "start", then the offset is relative to the beginning of the file. If it is "current", it is relative to the current access position in the file. If it is "end", then it is relative to the end-of-file (a negative is before the EOF, positive is after). If origin is omitted, start is assumed.

    The following options are recognized:

    -read - Place a read lock on the file. Multiple processes may be accessing the file with read-locks.

    -write - Place a write lock on the file. Only one process may be accessing a file if there is a write lock.

    -nowait - If specified, then the process will not block if the lock can not be obtained. With this option, the command returns 1 if the lock is obtained and 0 if it is not.

    See your system's fcntl system call documentation for full details of the behavior of file locking. If locking is being done on ranges of a file, it is best to use unbuffered file access (see the fcntl command).

for_file var filename { code }
    This procedure implements a loop over the contents of a file. For each line in filename, it sets var to the line and executes code.

    The break and continue commands work as with foreach.

    For example, the command

    	for_file line /etc/passwd {echo $line}

    would echo all the lines in the password file.

funlock fileId ?start? ?length? ?origin?
    Remove a locked from a file that was previously placed with the flock command. The arguments are the same as for the flock command, see that command for more details.

fstat fileId ?item?|?stat arrayvar?
    Obtain status information about an open file.

    The following keys are used to identify data items:

    o atime - The time of last access.

    o ctime - The time of last file status change

    o dev - The device containing a directory for the file. This value uniquely identifies the file system that contains the file.

    o gid - The group ID of the file's group.

    o ino - The inode number. This field uniquely identifies the file in a given file system.

    o mode - The mode of the file (see the mknod system call).

    o mtime - Time when the data in the file was last modified.

    o nlink - The number of links to the file.

    o size - The file size in bytes.

    o tty - If the file is associated with a terminal, then 1 otherwise 0.

    o type - The type of the file in symbolic form, which is one of the following values: file, directory, characterSpecial, blockSpecial, fifo, link, or socket.

    o uid - The user ID of the file's owner.

    If one of these keys is specified as item, then that data item is returned.

    If stat arrayvar is specified, then the information is returned in the array arrrayvar. Each of the above keys indexes an element of the array containing the data.

    If only fileId is specified, the command returns the data as a keyed list.

    The following value may be returned only if explicitly asked for, it will not be returned with the array or keyed list forms:

    o remotehost - If fileId is a TCP/IP socket connection, then a list is returned with the first element being the remote host IP address. If the remote host name can be found, it is returned as the second element of the list.

lgets fileId ?varName?
    Reads the next Tcl list from the file given by fileId and discards the terminating newline character. This command differs from the gets command, in that it reads Tcl lists rather than lines. If the list contains a newline, then that newline will be returned as part of the result. Only a newline not quoted as part of the list indicates the end of the list. There is no corresponding command for outputing lists, as puts will do this correctly. If varName is specified, then the line is placed in the variable by that name and the return value is a count of the number of characters read (not including the newline). If the end of the file is reached before reading any characters then -1 is returned and varName is set to an empty string. If varName is not specified then the return value will be the line (minus the newline character) or an empty string if the end of the file is reached before reading any characters. An empty string will also be returned if a line contains no characters except the newline, so eof may have to be used to determine what really happened.

frename oldPath newPath
    Renames oldPath to newPath. This command does not support renaming across file systems unless the rename system call supports them. If renaming accross file systems is desired, exec the mv command.

pipe ?fileId_var_r fileId_var_w?
    Create a pipe. If fileId_var_r and fileId_var_r are specified, then pipe will set the a variable named fileId_var_r to contain the fileId of the side of the pipe that was opened for reading, and fileId_var_w will contain the fileId of the side of the pipe that was opened for writing.

    If the fileId variables are not specified, then a list containing the read and write fileIdw is returned as the result of the command.

read_file ?-nonewline? fileName
    read_file fileName numBytes
    This proecure reads the file fileName and returns the contents as a string. If -nonewline is specified, then the last character of the file is discarded if it is a newline. The second form specifies exactly how many bytes will be read and returned, unless there are fewer than numBytes bytes left in the file; in this case, all the remaining bytes are returned.

select readfileIds ?writefileIds? ?exceptfileIds? ?timeout?
    This command allows an Extended Tcl program to wait on zero or more files being ready for for reading, writing, have an exceptional condition pending, or for a timeout period to expire. readFileIds, writeFileIds, exceptFileIds are each lists of fileIds, as returned from open, to query. An empty list ({}) may be specified if a category is not used.

    The files specified by the readFileIds list are checked to see if data is available for reading. The writeFileIds are checked if the specified files are clear for writing. The exceptFileIds are checked to see if an exceptional condition has occured (typically, an error). The write and exception checking is most useful on devices, however, the read checking is very useful when communicating with multiple processes through pipes. Select considers data pending in the stdio input buffer for read files as being ready for reading, the files do. not have to be unbuffered.

    Timeout is a floating point timeout value, in seconds. If an empty list is supplied (or the parameter is omitted), then no timeout is set. If the value is zero, then the select command functions as a poll of the files, returning immediately even if none are ready.

    If the timeout period expires with none of the files becomming ready, then the command returns an empty list. Otherwise the command returns a list of three elements, each of those elements is a list of the fileIds that are ready in the read, write and exception classes. If none are ready in a class, then that element will be the null list. For example:

            select {file3 file4 file5} {file6 file7} {} 10.5
    could return
            {file3 file4} {file6} {}
    or perhaps
            file3 {} {}

write_file fileName string ?string...?
    This procedure writes the specified strings to the named file.

TCP/IP SERVER ACCESS

A command is provided to access TCP/IP based servers. In addition it is easy to build servers using Extended Tcl that run under inetd. The fstat remotehost request is useful for these servers.

server_open ?option? host service
    Open a TCP/IP connection to a server of host on the port specified by service. The server is then accessed using the standard Tcl file I/O commands. Host may be a host name or an IP address. Port may be a port number of a service name. Option is one of -buf or -nobuf. If no options is specified, -buf is the default.

    If -buf is specified, then the file is buffered. In this case, a pair of Tcl file ids are returned in a list. The first id is open for read access, the second for write. When writing to the file, the flush command must be used to force data in the buffer to be sent to the server. The close command must be called against both file ids when through with the socket. Buffered access will result in significantly better performance when reading data and will also improve a series of writes being done with out intermixed reads. The fcntl command may be used to make one of these files unbuffered.

    If -nobuf is specified, then the file is unbuffered and a single file id, open for both reading and writing, is returned.

    If a host name is supplied and more that one address is valid for the host, the addresses will be tried until one can be connected to. Use the server_info command to obtain the list of valid address.

server_info addresses hostname
    server_info official_name hostname server_info aliases_name hostname
    Optain information about a TCP/IP server.

    If the addresses option is specified, the list of IP addresses for the hostname is returned.

    If the official_name option is specified, the official name for hostname is returned.

    If the aliases option is specified, a list of aliases for hostname is returned.

FILE SCANNING COMMANDS

These commands provide a facility to scan files, matching lines of the file against regular expressions and executing Tcl code on a match. With this facility you can use Tcl to do the sort of file processing that is traditionally done with awk. And since Tcl's approach is more declarative, some of the scripts that can be rather difficult to write in awk are simple to code in Tcl.

File scanning in Tcl centers around the concept of a scan context. A scan context contains one or more match statements, which associate regular expressions to scan for with Tcl code to be executed when the expressions are matched.

scancontext ?option?
    This command manages file scan contexts. A scan context is a collection of regular expressions and commands to execute when that regular expression matches a line of the file. A context may also have a single default match, to be applied against lines that do not match any of the regular expressions. Multiple scan contexts may be defined and they may be reused on multiple files. A scan context is identified by a context handle. The scancontext command takes the following forms:

scancontext create
    Create a new scan context. The scanmatch command is used to define patterns in the context. A contexthandle is returned, which the Tcl programmer uses to refer to the newly created scan context in calls to the Tcl file scanning commands.

scancontext delete contexthandle
    Delete the scan context identified by contexthandle, and free all of the match statements and compiled regular expressions associated with the specified context.

scanfile ?-copyfile copyFileId? contexthandle fileId
    Scan the file specified by fileId, starting from the current file position. Check all patterns in the scan context specified by contexthandle against it, executing the match commands corresponding to patterns matched.

    If the optional -copyfile argument is specified, the next argument is a file ID to which all lines not matched by any pattern (excluding the default pattern) are to be written.

scanmatch ?-nocase? contexthandle ?regexp? commands
    Specify Tcl commands, to be evaluated when regexp is matched by a scanfile command. The match is added to the scan context specified by contexthandle. Any number of match statements may be specified for a give context. Regexp is a regular expression (see the regexp command). If -nocase is specified as the first argument, the pattern is matched regardless of alphabetic case.

    If regexp is not specified, then a default match is specified for the scan context. The default match will be executed when a line of the file does not match any of the regular expressions in the current scancontext.

    The array matchInfo is available to the Tcl code that is executed when an expression matches (or defaults). It contans information about the file being scanned and where within it the expression was matched.

    matchInfo is local to the top level of the match command unless declared global at that level by the Tcl global command. If it is to be used as a global, it must be declared global before scanfile is called (since scanfile sets the matchInfo before the match code is executed, a subsequent global will override the local variable). The following array entries are available:

    matchInfo(line)
        Contains the text of the line of the file that was matched.

    matchInfo(offset)
        The byte offset into the file of the first character of the line that was matched.

    matchInfo(linenum)
        The line number of the line that was matched. This is relative to the first line scanned, which is usually, but not necessarily, the first line of the file. The first line is line number one.

    matchInfo(handle)
        The file id (handle) of the file currently being scanned.

    matchInfo(copyHandle)
        The file id (handle) of the file specified by the -copyfile option. The element does not exist if -copyfile was not specified.

    matchInfo(submatch0)
        Will contain the characters matching the first parenthesized subexpression. The second will be contained in submatch1, etc.

    matchInfo(subindex0)
        Will contain the a list of the starting and ending indices of the string matching the first parenthesized subexpression. The second will be contained in subindex1, etc.

All scanmatch patterns that match a line will be processed in the order in which their specifications were added to the scan context. The remainder of the scanmatch pattern-command pairs may be skipped for a file line if a continue is executed by the Tcl code of a preceding, matched pattern.

If a return is executed in the body of the match command, the scanfile command currently in progress returns, with the value passed to return as its return value.

MATH COMMANDS

Several extended math commands commands make many additional math functions available in TclX. In addition, a set of procedures provide command access to the math functions supported by the expr command.

The following procedures provide command interfaces to the expr math functions. They take the same arguments as the expr functions and may take expressions as arguments.

    abs	acos	asin	atan2
    atan	ceil	cos	cosh
    double	exp	floor	fmod
    hypot	int	log10	log
    pow	round	sin	sinh
    sqrt	tan	tanh

max num1 num2 ?..numN?
    Returns the argument that has the highest numeric value. The arguments, numN may be any interger or floating point values.

min num1 num2 ?..numN?
    Returns the argument that has the lowest numeric value. The arguments, numN may be any interger or floating point values.

random limit | seed ?seedval?
    Generate a pseudorandom integer number greater than or equal to zero and less than limit. If seed is specified, then the command resets the random number generator to a starting point derived from the seedval. This allows one to reproduce pseudorandom number sequences for testing purposes. If seedval is omitted, then the seed is set to a value based on current system state and the current time, providing a reasonably interesting and ever-changing seed.

LIST MANINIPULATION COMMANDS

Extended Tcl provides additional list manipulation commands and procedures.

intersect lista listb
    Procedure to return the logical intersection of two lists. The returned list will be sorted.

intersect3 lista listb
    Procedure to intersects two lists, returning a list containing three lists: The first list returned is everything in lista that wasn't in listb. The second list contains the intersection of the two lists, and the third list contains all the elements that were in listb but weren't in lista. The returned lists will be sorted.

lassign list var ?var...?
    Assign successive elements of a list to specified variables. If there are more variable names than fields, the remaining variables are set to the empty string. If there are more elements than variables, a list of the unassigned elements is returned.

    For example,

       lassign {dave 100 200 {Dave Foo}} name uid gid longName

    Assigns name to ``dave'', uid to ``100'', gid to ``200'', and longName to ``Dave Foo''.

lempty list
    Determine if the specified list is empty. If empty, 1 is returned, otherwise, 0 is returned. This command is an alternative to comparing a list to an empty string.

lmatch ?mode? list pattern
    Search the elements of list, returning a list of all elements matching pattern. If none match, an empty list is returned.

    The mode argument indicates how the elements of the list are to be matched against pattern and it must have one of the following values:

    -exact The list element must contain exactly the same string as pattern.

    -glob Pattern is a glob-style pattern which is matched against each list element using the same rules as the string match command.

    -regexp Pattern is treated as a regular expression and matched against each list element using the same rules as the regexp command.

    If mode is omitted then it defaults to -glob.

lrmdups list
    Procedure to remove duplicate elements from a list. The returned list will be sorted.

lvarcat var string ?string...?
    This command treats each string argument as a list and concatenates them to the end of the contents of var, forming a a single list. The list is stored back into var and also returned as the result. if var does not exist, it is created.

lvarpop var ?indexExpr? ?string?
    The lvarpop command pops (deletes) the element indexed by the expression indexExpr from the list contained in the variable var. If index is omitted, then 0 is assumed. If string, is specified, then the deleted element is replaced by string. The replaced or deleted element is returned. Thus ``lvarpop argv 0'' returns the first element of argv, setting argv to contain the remainder of the string.

    If the expression indexExpr starts with the string end, then end is replaced with the index of the last element in the list. If the expression starts with len, then len is replaced with the length of the list.

lvarpush var string ?indexExpr?
    The lvarpush command pushes (inserts) string as an element in the list contained in the variable var. The element is inserted before position indexExpr in the list. If index is omitted, then 0 is assumed. If var does not exists, it is created.

    If the expression indexExpr starts with the string end, then end is replaced with the index of the last element in the list. If the expression starts with len, then len is replaced with the length of the list. Note the a value of end means insert the string before the last element.

union lista listb
    Procedure to return the logical union of the two specified lists. Any duplicate elements are removed.

KEYED LISTS

Extended Tcl defines a special type of list referred to as keyed lists. These lists provided a structured data type built upon standard Tcl lists. This provides a functionality similar to structs in the C programming language.

A keyed list is a list in which each element contains a key and value pair. These element pairs are stored as lists themselves, where the key is the first element of the list, and the value is the second. The key-value pairs are refered to as fields. This is an example of a keyed list:

        {{NAME {Frank Zappa}} {JOB {musician and composer}}}

If the variable person contained the above list, then keylget person NAME would return {Frank Zappa}. Executing the command:

    keylset person ID 106

would make person contain

        {{ID 106} {NAME {Frank Zappa}} {JOB {musician and composer}}

Fields may contain subfields; `.' is the seperator character. Subfields are actually fields where the value is another keyed list. Thus the following list has the top level fields ID and NAME, and subfields NAME.FIRST and NAME.LAST:

        {ID 106} {NAME {{FIRST Frank} {LAST Zappa}}}

There is no limit to the recursive depth of subfields, allowing one to build complex data structures.

Keyed lists are constructed and accessed via a number of commands. All keyed list management commands take the name of the variable containing the keyed list as an argument (i.e. passed by reference), rather than passing the list directly.

keyldel listvar key
    Delete the field specified by key from the keyed list in the variable listvar. This removes both the key and the value from the keyed list.

keylget listvar ?key? ?retvar | {}?
    Return the value associated with key from the keyed list in the variable listvar. If retvar is not specified, then the value will be returned as the result of the command. In this case, if key is not found in the list, an error will result.

    If retvar is specified and key is in the list, then the value is returned in the variable retvar and the command returns 1 if the key was present within the list. If key isn't in the list, the command will return 0, and retvar will be left unchanged. If {} is specified for retvar, the value is not returned, allowing the Tcl programmer to determine if a key is present in a keyed list without setting a variable as a side-effect.

    If key is omitted, then a list of all the keys in the keyed list is returned.

keylkeys listvar ?key?
    Return the a list of the keyes in the keyed list in the variable listvar. If keys is specified, then it is the name of a key field who's subfield keys are to be retrieve.

keylset listvar key value ?key2 value2 ...?
    Set the value associated with key, in the keyed list contained in the variable listvar, to value. If listvar does not exists, it is created. If key is not currently in the list, it will be added. If it already exists, value replaces the existing value. Multiple keywords and values may be specified, if desired.

STRING AND CHARACTER MANIPULATION COMMANDS

The commands provide additional functionality to classify characters, convert characters between character and numeric values, index into a string, determine the length of a string, extract a range of character from a string, replicate a string a number of times, and transliterate a string (similar to the Unix tr program).

cequal string1 string2
    This command compares two strings for equality. Returns 1 if string1 and string2 are the identical and 0 if they are not. This command is a short-cut for string compare and avoids the problems with string expressions being treated unintentionally as numbers.

cindex string indexExpr
    Returns the character indexed by the expression indexExpr (zero based) from string.

    If the expression indexExpr starts with the string end, then end is replaced with the index of the last character in the string. If the expression starts with len, then len is replaced with the length of the string.

clength string
    Returns the length of string in characters. This command is a shortcut for:

        string length string

crange string firstExpr lastExpr
    Returns a range of characters from string starting at the character indexed by the expression firstExpr (zero-based) until the character indexed by the expression lastExpr.

    If the expression firstExpr or lastExpr starts with the string end, then end is replaced with the index of the last character in the string. If the expression starts with len, then len is replaced with the length of the string.

csubstr string firstExpr lengthExpr
    Returns a range of characters from string starting at the character indexed by the expression firstExpr (zero-based) for lengthExpr characters.

    If the expression firstExpr or lengthExpr starts with the string end, then end is replaced with the index of the last character in the string. If the expression starts with len, then len is replaced with the length of the string.

ctoken strvar separators
    Parse a token out of a character string. The string to parse is contained in the variable named strvar. The string separators contains all of the valid separator characters for tokens in the string. All leading separators are skipped and the first token is returned. The variable strvar will be modified to contain the remainder of the string following the token.

cexpand string
    Expand backslash sequences in string to there actual characters. No other substitution takes place.

ctype ?-failindex var? class string
    ctype determines whether all characters in string are of the specified class. It returns 1 if they are all of class, and 0 if they are not, or if the string is empty. This command also provides another method (besides format and scan) of converting between an ASCII character and its numeric value. The following ctype commands are available:

    ctype ?-failindex var? alnum string
        Tests that all characters are alphabetic or numeric characters as defined by the character set.

    ctype ?-failindex var? alpha string
        Tests that all characters are alphabetic characters as defined by the character set.

    ctype ?-failindex var? ascii string
        Tests that all characters are an ASCII character (a non-negative number less than 0200).

    ctype char number
        Converts the numeric value, string, to an ASCII character. Number must be in the range 0 through 255.

    ctype ?-failindex var? cntrl string
        Tests that all characters are ``control characters'' as defined by the character set.

    ctype ?-failindex var? digit string
        Tests that all characters are valid decimal digits, i.e. 0 through 9.

    ctype ?-failindex var? graph string
        Tests that all characters within are any character for which ctype print is true, except for space characters.

    ctype ?-failindex var? lower string
        Tests that all characters are lowercase letters as defined by the character set.

    ctype ord character
        Convert a character into its decimal numeric value. The first character of the string is converted.

    ctype ?-failindex var? space string
        Tests that all characters are either a space, horizontal-tab, carriage return, newline, vertical-tab, or form-feed.

    ctype ?-failindex var? print string
        Tests that all characters are a space or any character for which ctype alnum or ctype punct is true or other ``printing character'' as defined by the character set.

    ctype ?-failindex var? punct string
        Tests that all characters are made up of any of the characters other than the ones for which alnum, cntrl, or space is true.

    ctype ?-failindex var? upper string
        Tests that all characters are uppercase letters as defined by the character set.

    ctype ?-failindex var? xdigit string
        Tests that all characters are valid hexadecimal digits, that is 0 through 9, a through f or A through F.

    If -failindex is specified, then the index into string of the first character that did not match the class is returned in var.

replicate string countExpr
    Returns string, replicated the number of times indicated by the expression countExpr.

translit inrange outrange string
    Translate characters in string, changing characters occuring in inrange to the corresponding character in outrange. Inrange and outrange may be list of characters or a range in the form `A-M'. For example:
            translit a-z A-Z foobar
    returns "FOOBAR".

XPG/3 MESSAGE CATALOG COMMANDS

These commands provide a Tcl interface to message catalogs that are compliant with the X/Open Portability Guide, Version 3 (XPG/3).

Tcl programmers can use message catalogs to create applications that are language-independent. Through the use of message catalogs, prompts, messages, menus and so forth can exist for any number of languages, and they can altered, and new languages added, without affecting any Tcl or C source code, greatly easing the maintenance difficulties incurred by supporting multiple languages.

A default text message is passed to the command that fetches entries from message catalogs. This allows the Tcl programmer to create message catalogs containing messages in various languages, but still have a set of default messages available regardless of the presence of any message catalogs, and allow the programs to press on without difficulty when no catalogs are present.

Thus, the normal approach to using message catalogs is to ignore errors on catopen, in which case catgets will return the default message that was specified in the call.

The Tcl message catalog commands normally ignore most errors. If it is desirable to detect errors, a special option is provided. This is normally used only during debugging, to insure that message catalogs are being used. If your Unix implementation does not have XPG/3 message catalog support, stubs will be compiled in that will create a version of catgets that always returns the default string. This allows for easy porting of software to environments that don't have support for message catalogs.

Message catalogs are global to the process, an application with multiple Tcl interpreters within the same process may pass and share message catalog handles.

catopen ?-fail|-nofail? catname
    Open the message catalog catname. This may be a relative path name, in which case the NLSPATH environment variable is searched to find an absolute path to the message catalog. A handle in the form msgcatN is returned. Normally, errors are ignored, and in the case of a failed call to catopen, a handle is returned to an unopened message catalog. (This handle may still be passed to catgets and catclose, causing catgets to simply return the default string, as described above. If the -fail option is specified, an error is returned if the open fails. The option -nofail specifies the default behavior of not returning an error when catopen fails to open a specified message catalog. If the handle from a failed catopen is passed to catgets, the default string is returned.

catgets catHandle setnum msgnum defaultstr
    Retrieve a message form a message catalog. CatHandle should be a Tcl message catalog handle that was returned by catopen. Setnum is the message set number, and msgnum is the message number. If the message catalog was not opened, or the message set or message number cannot be found, then the default string, defaultstr, is returned.

catclose ?-fail|-nofail? cathandle
    Close the message catalog specified by cathandle. Normally, errors are ignored. If -fail is specified, any errors closing the message catalog file are returned. The option -nofail specifies the default behavior of not returning an error. The use of -fail only makes sense if it was also specified in the call to catopen.

EXTENDED TCL SHELL

tcl ?-qn? ?-f? script?|?-c command? ?args?

Tcl starts the interactive Tcl command interpreter. The Tcl shell provides an environment for writing, debugging and executing Tcl scripts. The functionality of the Tcl shell can be easily obtained by any application that includes Tcl.

The tcl command, issued without any arguments, invokes an interactive Tcl shell, allowing the user to interact directly with Tcl, executing any Tcl commands at will and viewing their results.

If script is specified, then the script is executed non-interactively with any additional arguments, args, being supplied in the global Tcl variable `argv'. If command is supplied, then this command (or semicolon-separated series of commands) is executed, with `argv' containing any args.

The Tcl shell is intended as an environment for Tcl program development and execution. While it is not a full-featured interactive shell, it provides a comfortable environment for the interactive development of Tcl code. Note that the package library code described here overrides the unknown command provided as part of the standard Berkeley Tcl library facility, although Tcl source libraries coded to that standard can be loaded and used by Extended Tcl.

The following command line flags are recognized by the Tcl shell command line parser:

-q  Quick initialization flag. The Tcl initiaization file is not evaluated and the auto_path variable is not set. Tcl auto-load libraries will not be available.

-n  No procedure call stack dump. The procedure call stack will not be displayed when an error occurs, only the error message. Useful in the #! line of already debugged scripts.

-f  Takes the next argument as a script for Tcl to source, rather than entering interactive mode. The -f flag is optional. Normally the first argument that does not start with a `-' is taken as the script to execute unless the `-c' option is specified. Any following arguments are passed to the script via argv, thus any other Tcl shell command-line flags must precede this option.

-c  Take the next argument as a Tcl command to execute. It may contain series of commands to execute, separated by `;'. Any following arguments are passed in argv, thus, as with -f, any other Tcl shell flags must precede this option.

--  Mark the end of the arguments to the Tcl shell. All arguments following this are passed in the Tcl variable argv. This is useful to pass arguments without attempting to execute a Tcl script.

The result string returned by a command executed from the Tcl shell command line is normally echoed back to the user. If an error occurs, then the string result is displayed, along with the error message. The error message will be preceded by the string ``Error:''.

The set command is a special case. If the command is called to set a variable (i.e. with two arguments), then the result will not be echoed. If only one argument, the name of a variable, is supplied to set, then the result will be echoed.

If an unknown Tcl command is entered from the command line, then the Unix command path, specified in the environment variable PATH, will be searched for a command of the same name. If the command is found, it will be executed with any arguments remaining on the Tcl command line being passed as arguments to the command. This feature is provided to enhance the interactive environment for developing Tcl scripts.

Automatic execution of programs in this manner is only supported from the command line, not in script files or in procedures, to reduce confusion and mistakes while programming in Tcl. Scripts should use the Tcl exec or system commands to run Unix commands.

The following variables are set and/or used by the Tcl shell.

argv0
    Contains the name of the Tcl program specified on the command line or the name that the Tcl shell was invoked under if no program was specified. argc Contains a count of the number of argv arguments (0 if none). argv A list containing the arguments passed in from the command line, excluding arguments used by the Tcl shell. The first element is the first passed argument, not the program name.

tcl_interactive
    Set to 1 if Tcl shell is invoked interactively, or 0 if the Tcl shell is directly executing a script. Normally checked by scripts so that they can function as a standalone application if specified on the command line, but merely load in and not execute if loaded during an interactive invocation of Tcl.

auto_path
    Path to search to locate Tcl scripts. Used by the auto_load command and the TclX unknown command handler. The path is a Tcl list of directory names.

tcl_prompt1
    Contains code to run to output the prompt used when interactively prompting for commands.

tcl_prompt2
    Contains code to run to output the prompt used when interactively prompting for continuation of an incomplete command.

TCLXENV
    Array that contains information used internally by various Tcl procedures that are part of the TclX shell. Don't change this array unless you know what your doing.

When Extended Tcl is installed, the standard runtime files are places in the Tcl master directory, which is configured when Tcl is built. This master directory normally contains the Tcl initialization file (TclInit.tcl), the standard Tcl library file (tcl.tlib) and the help files. The Tcl master directory is named after the version of Tcl it is associated with, e.g. /usr/local/tclX/7.0a. The path to the Tcl master directory is available from the info library command. The location of the Tcl master directory can be overridden with the TCL_LIBRARY environment variable.

The first step in initializing the Tcl shell is to locate the Tcl initialization file, normally TclInit.tcl. If an environment variable TCLINIT exists, it contains the path to the Tcl initialization file. If the TCLINIT environment variable is not set, the file TclInit.tcl is used from the default Tcl master directory.

Tcl then evaulates the Tcl initialization file. The auto_path variable is initialized to the Tcl master directory and may be augmented by the intialization file or the application. Other procedures and variables used by the Extended Tcl shell are also defined by this file.

If the Tcl is invoked interactively, it will source a file named .tclrc in the user's home directory, if it exists. Tcl is viewed primarily as a programming language, not an interactive shell, so the .tclrc is intended for use for loading development utilities, not to support applications, which should not have to rely on the user's environment in such a manner.

The Extended Tcl Tk shell, wishx, has an additional master directory and initialization file. It use the environment variable TK_LIBRARY to override the default location of the Tk master directory.

HELP FACILITY

The help facility allows one to look up help pages which where extracted from the standard Tcl manual pages and Tcl scripts during Tcl installation. Help files are structured as a multilevel tree of subjects and help pages. Help files are found by searching directories named help in the directories listed in the auto_path variable. All of the files in the list of help directories form a virtual root of the help tree. This method allows multiple applications to provide help trees without having the files reside in the same directory.

The help facility can be accessed in two ways, as interactive commands in the Extended Tcl shell or as an interactive Tk-based program (if you have built Extended Tcl with Tk).

To run the Tk-based interactive help program:

    tclhelp ?addpaths?
Where addpaths are additional paths to search for help directories. By default, only the auto_path used by tclhelp is search. This will result in help on Tcl, Extended Tcl and Tk.

The following interactive Tcl commands and options are provided with the help package:

help
    Help, without arguments, lists of all the help subjects and pages under the current help subject.

help subject
    Displays all of help pages and lower level subjects (if any exist) under the subject subject.

help subject/helppage
    Display the specified help page. The help output is passed through a simple pager if output exceeds 23 lines, pausing waiting for a return to be entered. If any other character is entered, the output is terminated.

helpcd ?subject?
    Change the current subject, which is much like the Unix current directory. If subject is not specified, return to the top-level of the help tree. Help subject path names may also include ``..'' elements.

helppwd
    Displays the current help subject.

help help | ?
    Displays help on the help facility at any directory level.

apropos pattern
    This command locates subjects by searching their one-line descriptions for a pattern. Apropos is useful when you can remember part of the name or description of a command, and want to search through the one-line summaries for matching lines. Full regular expressions may be specified (see the regexp command).

TCL LOADABLE LIBRARIES AND PACKAGES

Extended Tcl supports standard Tcl tclIndex libraries and package libraries. A package library file can contain multiple independent Tcl packages. A package is a named collection of related Tcl procedures and initialization code.

The package library file is just a regular Unix text file, editable with your favorite text editor, containing packages of Tcl source code. The package library file name must have the suffix .tlib. An index file with the suffix .tndx, corresponding to the package library. The .tndx will be automatically created by Tcl whenever it is out of date or missing (provided there is write access to the directory.

The variable auto_path contains a list of directories that are searched for libraries. The first time an unknown command trap is take, the indexes for the libraries are loaded into memory. If the auto_path variable is changed during execution of a program, it will be re-searched. Only the first package of a given name found during the execution of a program is loaded. This can be overridden with loadlibindex command.

The start of a package is delimited by:

    #@package: package_name proc1 ?..procN?

These lines must start in column one. Everything between the #@package: keyword and the next #@package: keyword or a #@packend keyword, or the end of the file, becomes part of the named package. The specified procedures, proc1..procN, are the entry points of the package. When a command named in a package specification is executed and detected as an unknown command, all code in the specified package will be sourced. This package should define all of the procedures named on the package line, define any support procedures required by the package and do any package-specific initialization. Packages declarations maybe continued on subsequent lines using standard Tcl backslash line continuations. The #@packend keyword is useful to make sure only the minimum required section of code is sourced. Thus for example a large comment block at the beginning of the next file won't be loaded.

Care should be taken in defining package_name, as the first package found in the path by with a given name is loaded. This can be useful in developing new version of packages installed on the system.

For example, in a package source file, the presence of the following line:

    #@package: directory_stack pushd popd dirs

says that the text lines following that line in the package file up to the next package line or the end of the file is a package named directory_stack and that an attempt to execute either pushd, popd or dirs when the routine is not already defined will cause the directory_stack portion of the package file to be loaded.

PACKAGE LIBRARY MANAGEMENT COMMANDS

Several commands are available for building and managing package libraries. Commands that are extended versions of the standard Tcl library commands are listed here. All of the standard Tcl library management commands and variables are also supported.

auto_commands ?-loaders?
    Lists the names of all known loadable procedures and commands procedures. If -loaders is specified, the command that will be executed to load the command will also be returned.

buildpackageindex libfilelist
    Build index files for package libraries. The argument libfilelist is a list of package libraries. Each name must end with the suffix .tlib. A corresponding .tndx file will be built. The user must have write access to the directory containing each library.

convert_lib tclIndex packagelib ?ignore?
    Convert a Ousterhout style tclIndex index file and associate source files into a package library packagelib. If packagelib does not have a .tlib extension, one will be added. Any files specified in tclIndex that are in the list ignore will be skipped. Files listed in ignore should just be the base file names, not full paths.

auto_load ?command?
    Attempt to load the specified command from a loadable library. loading the package containing the procedure. If the package indexes have not been loaded for all package libraries in auto_path, they will be loaded. Out-of-date library indexes will be rebuilt if they are writable. The procedure returns 1 if the command was sucessfully loaded, or 0 if it was not.

    Duplicated package names are skipped, the first package of a given name found in the path is loaded. If the auto_path has changed since the last load, indexes will be reloaded (duplicate packages will not be redefined).

    If command is not specified, the indexes will be loaded, if they have not alreay been loaded or if the auto_path variable has changed, but no command will be loaded.

This command overrides the standard Tcl procedure of the same name.

loadlibindex libfile.tlib
    Load the package library index of the library file libfile (which must have the suffix .tlib). Package library indexes along the auto_path are loaded automatically on the first demand_load; this command is provided to explicitly load libraries that are not in the path. If the index file (with a .tndx suffix) does not exists or is out of date, it will be rebuilt if the user has directory permissions to create it. If a package with the same name as a package in libfile.tlib has already been loaded, its definition will be overridden by the new package. However, if any procedure has actually been used from the previously defined package, the procedures from libfile.tlib will not be loaded.

    This command will also load an index built by mkindex.tcl program supplied with standard Tcl. This file must be named "tclIndex".

auto_packages ?-location?
    Returns a list of the names of all defined packages. If -location is specified, a list of pairs of package name and the .tlib path name, offset and length of the package within the library.

auto_load_file file
    Source a file, as with the source command, except search auto_path for the file.

searchpath path file
    Search all directories in the specified path, which is a Tcl list, for the specified file. Returns the full path name of the file, or an empty string if the requested file could not be found.