403acdc0da
as I get these back down to my machine.
186 lines
6.6 KiB
Plaintext
186 lines
6.6 KiB
Plaintext
'\"
|
|
'\" Copyright (c) 1993 The Regents of the University of California.
|
|
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
|
|
'\"
|
|
'\" See the file "license.terms" for information on usage and redistribution
|
|
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
|
|
'\"
|
|
'\" SCCS: @(#) exec.n 1.12 96/03/25 20:13:20
|
|
'\"
|
|
.so man.macros
|
|
.TH exec n 7.0 Tcl "Tcl Built-In Commands"
|
|
.BS
|
|
'\" Note: do not modify the .SH NAME line immediately below!
|
|
.SH NAME
|
|
exec \- Invoke subprocess(es)
|
|
.SH SYNOPSIS
|
|
\fBexec \fR?\fIswitches\fR? \fIarg \fR?\fIarg ...\fR?
|
|
.BE
|
|
|
|
.SH DESCRIPTION
|
|
.PP
|
|
This command treats its arguments as the specification
|
|
of one or more subprocesses to execute.
|
|
The arguments take the form of a standard shell pipeline
|
|
where each \fIarg\fR becomes one word of a command, and
|
|
each distinct command becomes a subprocess.
|
|
.PP
|
|
If the initial arguments to \fBexec\fR start with \fB\-\fR then
|
|
.VS
|
|
they are treated as command-line switches and are not part
|
|
of the pipeline specification. The following switches are
|
|
currently supported:
|
|
.TP 13
|
|
\fB\-keepnewline\fR
|
|
Retains a trailing newline in the pipeline's output.
|
|
Normally a trailing newline will be deleted.
|
|
.TP 13
|
|
\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.
|
|
.VE
|
|
.PP
|
|
If an \fIarg\fR (or pair of \fIarg\fR's) has one of the forms
|
|
described below then it is used by \fBexec\fR to control the
|
|
flow of input and output among the subprocess(es).
|
|
Such arguments will not be passed to the subprocess(es). In forms
|
|
.VS
|
|
such as ``< \fIfileName\fR'' \fIfileName\fR may either be in a
|
|
separate argument from ``<'' or in the same argument with no
|
|
intervening space (i.e. ``<\fIfileName\fR'').
|
|
.VE
|
|
.TP 15
|
|
|
|
|
Separates distinct commands in the pipeline. The standard output
|
|
of the preceding command will be piped into the standard input
|
|
of the next command.
|
|
.TP 15
|
|
|&
|
|
Separates distinct commands in the pipeline. Both standard output
|
|
and standard error of the preceding command will be piped into
|
|
the standard input of the next command.
|
|
This form of redirection overrides forms such as 2> and >&.
|
|
.TP 15
|
|
<\0\fIfileName\fR
|
|
The file named by \fIfileName\fR is opened and used as the standard
|
|
input for the first command in the pipeline.
|
|
.TP 15
|
|
<@\0\fIfileId\fR
|
|
.VS
|
|
\fIFileId\fR must be the identifier for an open file, such as the return
|
|
value from a previous call to \fBopen\fR.
|
|
It is used as the standard input for the first command in the pipeline.
|
|
\fIFileId\fR must have been opened for reading.
|
|
.VE
|
|
.TP 15
|
|
<<\0\fIvalue\fR
|
|
\fIValue\fR is passed to the first command as its standard input.
|
|
.TP 15
|
|
>\0\fIfileName\fR
|
|
Standard output from the last command is redirected to the file named
|
|
\fIfileName\fR, overwriting its previous contents.
|
|
.TP 15
|
|
2>\0\fIfileName\fR
|
|
.VS
|
|
Standard error from all commands in the pipeline is redirected to the
|
|
file named \fIfileName\fR, overwriting its previous contents.
|
|
.TP 15
|
|
>&\0\fIfileName\fR
|
|
Both standard output from the last command and standard error from all
|
|
commands are redirected to the file named \fIfileName\fR, overwriting
|
|
its previous contents.
|
|
.VE
|
|
.TP 15
|
|
>>\0\fIfileName\fR
|
|
Standard output from the last command is
|
|
redirected to the file named \fIfileName\fR, appending to it rather
|
|
than overwriting it.
|
|
.TP 15
|
|
2>>\0\fIfileName\fR
|
|
.VS
|
|
Standard error from all commands in the pipeline is
|
|
redirected to the file named \fIfileName\fR, appending to it rather
|
|
than overwriting it.
|
|
.TP 15
|
|
>>&\0\fIfileName\fR
|
|
Both standard output from the last command and standard error from
|
|
all commands are redirected to the file named \fIfileName\fR,
|
|
appending to it rather than overwriting it.
|
|
.TP 15
|
|
>@\0\fIfileId\fR
|
|
\fIFileId\fR must be the identifier for an open file, such as the return
|
|
value from a previous call to \fBopen\fR.
|
|
Standard output from the last command is redirected to \fIfileId\fR's
|
|
file, which must have been opened for writing.
|
|
.TP 15
|
|
2>@\0\fIfileId\fR
|
|
\fIFileId\fR must be the identifier for an open file, such as the return
|
|
value from a previous call to \fBopen\fR.
|
|
Standard error from all commands in the pipeline is
|
|
redirected to \fIfileId\fR's file.
|
|
The file must have been opened for writing.
|
|
.TP 15
|
|
>&@\0\fIfileId\fR
|
|
\fIFileId\fR must be the identifier for an open file, such as the return
|
|
value from a previous call to \fBopen\fR.
|
|
Both standard output from the last command and standard error from
|
|
all commands are redirected to \fIfileId\fR's file.
|
|
The file must have been opened for writing.
|
|
.VE
|
|
.PP
|
|
If standard output has not been redirected then the \fBexec\fR
|
|
command returns the standard output from the last command
|
|
in the pipeline.
|
|
If any of the commands in the pipeline exit abnormally or
|
|
are killed or suspended, then \fBexec\fR will return an error
|
|
and the error message will include the pipeline's output followed by
|
|
error messages describing the abnormal terminations; the
|
|
\fBerrorCode\fR variable will contain additional information
|
|
about the last abnormal termination encountered.
|
|
If any of the commands writes to its standard error file and that
|
|
standard error isn't redirected,
|
|
then \fBexec\fR will return an error; the error message
|
|
will include the pipeline's standard output, followed by messages
|
|
about abnormal terminations (if any), followed by the standard error
|
|
output.
|
|
.PP
|
|
If the last character of the result or error message
|
|
is a newline then that character is normally deleted
|
|
from the result or error message.
|
|
This is consistent with other Tcl return values, which don't
|
|
normally end with newlines.
|
|
.VS
|
|
However, if \fB\-keepnewline\fR is specified then the trailing
|
|
newline is retained.
|
|
.VE
|
|
.PP
|
|
If standard input isn't redirected with ``<'' or ``<<''
|
|
or ``<@'' then the standard input for the first command in the
|
|
pipeline is taken from the application's current standard input.
|
|
.PP
|
|
If the last \fIarg\fR is ``&'' then the pipeline will be
|
|
executed in background.
|
|
.VS
|
|
In this case the \fBexec\fR command will return a list whose
|
|
elements are the process identifiers for all of the subprocesses
|
|
in the pipeline.
|
|
.VE
|
|
The standard output from the last command in the pipeline will
|
|
go to the application's standard output if it hasn't been
|
|
redirected, and error output from all of
|
|
the commands in the pipeline will go to the application's
|
|
standard error file unless redirected.
|
|
.PP
|
|
The first word in each command is taken as the command name;
|
|
tilde-substitution is performed on it, and if the result contains
|
|
no slashes then the directories
|
|
in the PATH environment variable are searched for
|
|
an executable by the given name.
|
|
If the name contains a slash then it must refer to an executable
|
|
reachable from the current directory.
|
|
No ``glob'' expansion or other shell-like substitutions
|
|
are performed on the arguments to commands.
|
|
|
|
.SH KEYWORDS
|
|
execute, pipeline, redirection, subprocess
|