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diff --git a/doc/process.n b/doc/process.n new file mode 100644 index 0000000..165e413 --- /dev/null +++ b/doc/process.n @@ -0,0 +1,150 @@ +'\" +'\" Copyright (c) 2017 Frederic Bonnet. +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +.TH process n 8.7 Tcl "Tcl Built-In Commands" +.so man.macros +.BS +'\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +tcl::process \- Subprocess management +.SH SYNOPSIS +\fB::tcl::process \fIoption \fR?\fIarg arg ...\fR? +.BE +.SH DESCRIPTION +.PP +This command provides a way to manage subprocesses created by the \fBopen\fR +and \fBexec\fR commands, as identified by the process identifiers (PIDs) of +those subprocesses. The legal \fIoptions\fR (which may be abbreviated) are: +.TP +\fB::tcl::process autopurge\fR ?\fIflag\fR? +. +Automatic purge facility. If \fIflag\fR is specified as a boolean value then +it activates or deactivate autopurge. In all cases it returns the current +status as a boolean value. When autopurge is active, +\fBTcl_ReapDetachedProcs\fR is called each time the \fBexec\fR command is +executed or a pipe channel created by \fBopen\fR is closed. When autopurge is +inactive, \fB::tcl::process\fR purge must be called explicitly. By default +autopurge is active. +.TP +\fB::tcl::process list\fR +. +Returns the list of subprocess PIDs. This includes all currently executing +subprocesses and all terminated subprocesses that have not yet had their +corresponding process table entries purged. +.TP +\fB::tcl::process purge\fR ?\fIpids\fR? +. +Cleans up all data associated with terminated subprocesses. If \fIpids\fR is +specified as a list of PIDs then the command only cleanup data for the matching +subprocesses if they exist, and raises an error otherwise. If a process listed is +still active, this command does nothing to that process. +.TP +\fB::tcl::process status\fR ?\fIswitches\fR? ?\fIpids\fR? +. +Returns a dictionary mapping subprocess PIDs to their respective status. If +\fIpids\fR is specified as a list of PIDs then the command only returns the +status of the matching subprocesses if they exist, and raises an error +otherwise. For active processes, the status is an empty value. For terminated +processes, the status is a list with the following format: +.QW "\fB{\fIcode\fR ?\fImsg errorCode\fR?\fB}\fR" , +where: +.RS +.TP +\fIcode\fR\0 +. +is a standard Tcl return code, i.e., \fB0\fR for TCL_OK and \fB1\fR +for TCL_ERROR, +.TP +\fImsg\fR\0 +. +is the human-readable error message, +.TP +\fIerrorCode\fR\0 +. +uses the same format as the \fBerrorCode\fR global variable +.PP +Note that \fBmsg\fR and \fBerrorCode\fR are only present for abnormally +terminated processes (i.e. those where the \fIcode\fR is nonzero). Under the +hood this command calls \fBTcl_WaitPid\fR with the \fBWNOHANG\fR flag set for +non-blocking behavior, unless the \fB\-wait\fR switch is set (see below). +.PP +Additionally, \fB::tcl::process status\fR accepts the following switches: +.TP +\fB\-wait\fR\0 +. +By default the command returns immediately (the underlying \fBTcl_WaitPid\fR is +called with the \fBWNOHANG\fR flag set) unless this switch is set. If \fIpids\fR +is specified as a list of PIDs then the command waits until the status of the +matching subprocesses are available. If \fIpids\fR was not specified, this +command will wait for all known subprocesses. +.TP +\fB\-\|\-\fR +. +Marks the end of switches. The argument following this one will +be treated as the first \fIarg\fR even if it starts with a \fB\-\fR. +.RE +.SH "EXAMPLES" +.PP +These show the use of \fB::tcl::process\fR. Some of the results from +\fB::tcl::process status\fR are split over multiple lines for readability. +.PP +.CS +\fB::tcl::process autopurge\fR + \fI\(-> true\fR +\fB::tcl::process autopurge\fR false + \fI\(-> false\fR + +set pid1 [exec command1 a b c | command2 d e f &] + \fI\(-> 123 456\fR +set chan [open "|command1 a b c | command2 d e f"] + \fI\(-> file123\fR +set pid2 [pid $chan] + \fI\(-> 789 1011\fR + +\fB::tcl::process list\fR + \fI\(-> 123 456 789 1011\fR + +\fB::tcl::process status\fR + \fI\(-> 123 0 + 456 {1 "child killed: write on pipe with no readers" { + CHILDKILLED 456 SIGPIPE "write on pipe with no readers"}} + 789 {1 "child suspended: background tty read" { + CHILDSUSP 789 SIGTTIN "background tty read"}} + 1011 {}\fR + +\fB::tcl::process status\fR 123 + \fI\(-> 123 0\fR + +\fB::tcl::process status\fR 1011 + \fI\(-> 1011 {}\fR + +\fB::tcl::process status\fR -wait + \fI\(-> 123 0 + 456 {1 "child killed: write on pipe with no readers" { + CHILDKILLED 456 SIGPIPE "write on pipe with no readers"}} + 789 {1 "child suspended: background tty read" { + CHILDSUSP 789 SIGTTIN "background tty read"}} + 1011 {1 "child process exited abnormally" { + CHILDSTATUS 1011 -1}}\fR + +\fB::tcl::process status\fR 1011 + \fI\(-> 1011 {1 "child process exited abnormally" { + CHILDSTATUS 1011 -1}}\fR + +\fB::tcl::process purge\fR +exec command1 1 2 3 & + \fI\(-> 1213\fR +\fB::tcl::process list\fR + \fI\(-> 1213\fR +.CE +.SH "SEE ALSO" +exec(n), open(n), pid(n), +Tcl_DetachPids(3), Tcl_WaitPid(3), Tcl_ReapDetachedProcs(3) +.SH "KEYWORDS" +background, child, detach, process, wait +'\" Local Variables: +'\" mode: nroff +'\" End: |