'\" '\" Copyright (c) 1993 The Regents of the University of California. '\" Copyright (c) 1994-1996 Sun Microsystems, Inc. '\" Copyright (c) 2006 Donal K. Fellows. '\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" .TH exec 3tcl 8.5 Tcl "Tcl Built-In Commands" .\" The -*- nroff -*- definitions below are for supplemental macros used .\" in Tcl/Tk manual entries. .\" .\" .AP type name in/out ?indent? .\" Start paragraph describing an argument to a library procedure. .\" type is type of argument (int, etc.), in/out is either "in", "out", .\" or "in/out" to describe whether procedure reads or modifies arg, .\" and indent is equivalent to second arg of .IP (shouldn't ever be .\" needed; use .AS below instead) .\" .\" .AS ?type? ?name? .\" Give maximum sizes of arguments for setting tab stops. Type and .\" name are examples of largest possible arguments that will be passed .\" to .AP later. If args are omitted, default tab stops are used. .\" .\" .BS .\" Start box enclosure. From here until next .BE, everything will be .\" enclosed in one large box. .\" .\" .BE .\" End of box enclosure. .\" .\" .CS .\" Begin code excerpt. .\" .\" .CE .\" End code excerpt. .\" .\" .VS ?version? ?br? .\" Begin vertical sidebar, for use in marking newly-changed parts .\" of man pages. The first argument is ignored and used for recording .\" the version when the .VS was added, so that the sidebars can be .\" found and removed when they reach a certain age. If another argument .\" is present, then a line break is forced before starting the sidebar. .\" .\" .VE .\" End of vertical sidebar. .\" .\" .DS .\" Begin an indented unfilled display. .\" .\" .DE .\" End of indented unfilled display. .\" .\" .SO ?manpage? .\" Start of list of standard options for a Tk widget. The manpage .\" argument defines where to look up the standard options; if .\" omitted, defaults to "options". The options follow on successive .\" lines, in three columns separated by tabs. .\" .\" .SE .\" End of list of standard options for a Tk widget. .\" .\" .OP cmdName dbName dbClass .\" Start of description of a specific option. cmdName gives the .\" option's name as specified in the class command, dbName gives .\" the option's name in the option database, and dbClass gives .\" the option's class in the option database. .\" .\" .UL arg1 arg2 .\" Print arg1 underlined, then print arg2 normally. .\" .\" .QW arg1 ?arg2? .\" Print arg1 in quotes, then arg2 normally (for trailing punctuation). .\" .\" .PQ arg1 ?arg2? .\" Print an open parenthesis, arg1 in quotes, then arg2 normally .\" (for trailing punctuation) and then a closing parenthesis. .\" .\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. .if t .wh -1.3i ^B .nr ^l \n(.l .ad b .\" # Start an argument description .de AP .ie !"\\$4"" .TP \\$4 .el \{\ . ie !"\\$2"" .TP \\n()Cu . el .TP 15 .\} .ta \\n()Au \\n()Bu .ie !"\\$3"" \{\ \&\\$1 \\fI\\$2\\fP (\\$3) .\".b .\} .el \{\ .br .ie !"\\$2"" \{\ \&\\$1 \\fI\\$2\\fP .\} .el \{\ \&\\fI\\$1\\fP .\} .\} .. .\" # define tabbing values for .AP .de AS .nr )A 10n .if !"\\$1"" .nr )A \\w'\\$1'u+3n .nr )B \\n()Au+15n .\" .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n .nr )C \\n()Bu+\\w'(in/out)'u+2n .. .AS Tcl_Interp Tcl_CreateInterp in/out .\" # BS - start boxed text .\" # ^y = starting y location .\" # ^b = 1 .de BS .br .mk ^y .nr ^b 1u .if n .nf .if n .ti 0 .if n \l'\\n(.lu\(ul' .if n .fi .. .\" # BE - end boxed text (draw box now) .de BE .nf .ti 0 .mk ^t .ie n \l'\\n(^lu\(ul' .el \{\ .\" Draw four-sided box normally, but don't draw top of .\" box if the box started on an earlier page. .ie !\\n(^b-1 \{\ \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' .\} .el \}\ \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' .\} .\} .fi .br .nr ^b 0 .. .\" # VS - start vertical sidebar .\" # ^Y = starting y location .\" # ^v = 1 (for troff; for nroff this doesn't matter) .de VS .if !"\\$2"" .br .mk ^Y .ie n 'mc \s12\(br\s0 .el .nr ^v 1u .. .\" # VE - end of vertical sidebar .de VE .ie n 'mc .el \{\ .ev 2 .nf .ti 0 .mk ^t \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n' .sp -1 .fi .ev .\} .nr ^v 0 .. .\" # Special macro to handle page bottom: finish off current .\" # box/sidebar if in box/sidebar mode, then invoked standard .\" # page bottom macro. .de ^B .ev 2 'ti 0 'nf .mk ^t .if \\n(^b \{\ .\" Draw three-sided box if this is the box's first page, .\" draw two sides but no top otherwise. .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c .\} .if \\n(^v \{\ .nr ^x \\n(^tu+1v-\\n(^Yu \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c .\} .bp 'fi .ev .if \\n(^b \{\ .mk ^y .nr ^b 2 .\} .if \\n(^v \{\ .mk ^Y .\} .. .\" # DS - begin display .de DS .RS .nf .sp .. .\" # DE - end display .de DE .fi .RE .sp .. .\" # SO - start of list of standard options .de SO 'ie '\\$1'' .ds So \\fBoptions\\fR 'el .ds So \\fB\\$1\\fR .SH "STANDARD OPTIONS" .LP .nf .ta 5.5c 11c .ft B .. .\" # SE - end of list of standard options .de SE .fi .ft R .LP See the \\*(So manual entry for details on the standard options. .. .\" # OP - start of full description for a single option .de OP .LP .nf .ta 4c Command-Line Name: \\fB\\$1\\fR Database Name: \\fB\\$2\\fR Database Class: \\fB\\$3\\fR .fi .IP .. .\" # CS - begin code excerpt .de CS .RS .nf .ta .25i .5i .75i 1i .. .\" # CE - end code excerpt .de CE .fi .RE .. .\" # UL - underline word .de UL \\$1\l'|0\(ul'\\$2 .. .\" # QW - apply quotation marks to word .de QW .ie '\\*(lq'"' ``\\$1''\\$2 .\"" fix emacs highlighting .el \\*(lq\\$1\\*(rq\\$2 .. .\" # PQ - apply parens and quotation marks to word .de PQ .ie '\\*(lq'"' (``\\$1''\\$2)\\$3 .\"" fix emacs highlighting .el (\\*(lq\\$1\\*(rq\\$2)\\$3 .. .\" # QR - quoted range .de QR .ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3 .\"" fix emacs highlighting .el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3 .. .\" # MT - "empty" string .de MT .QW "" .. .BS '\" Note: do not modify the .SH NAME line immediately below! .SH NAME exec \- Invoke subprocesses .SH SYNOPSIS \fBexec \fR?\fIswitches\fR? \fIarg \fR?\fIarg ...\fR? ?\fB&\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 they are treated as command-line switches and are not part of the pipeline specification. The following switches are currently supported: .TP 13 \fB\-ignorestderr\fR . Stops the \fBexec\fR command from treating the output of messages to the pipeline's standard error channel as an error case. .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. .PP If an \fIarg\fR (or pair of \fIarg\fRs) 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 such as .QW "\fB<\fR \fIfileName\fR" , \fIfileName\fR may either be in a separate argument from .QW \fB<\fR or in the same argument with no intervening space (i.e. .QW \fB<\fIfileName\fR ). .TP 15 \fB|\fR . 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 \fB|&\fR . 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 \fB<\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 \fB<@\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. It is used as the standard input for the first command in the pipeline. \fIFileId\fR must have been opened for reading. .TP 15 \fB<<\0\fIvalue\fR . \fIValue\fR is passed to the first command as its standard input. .TP 15 \fB>\0\fIfileName\fR . Standard output from the last command is redirected to the file named \fIfileName\fR, overwriting its previous contents. .TP 15 \fB2>\0\fIfileName\fR . Standard error from all commands in the pipeline is redirected to the file named \fIfileName\fR, overwriting its previous contents. .TP 15 \fB>&\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. .TP 15 \fB>>\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 \fB2>>\0\fIfileName\fR . 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 \fB>>&\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 \fB>@\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 \fB2>@\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 \fB2>@1\0\fR . Standard error from all commands in the pipeline is redirected to the command result. This operator is only valid at the end of the command pipeline. .TP 15 \fB>&@\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. .PP If standard output has not been redirected then the \fBexec\fR command returns the standard output from the last command in the pipeline, unless .QW 2>@1 was specified, in which case standard error is included as well. 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 \fB\-errorcode\fR return option 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 is not redirected and \fB\-ignorestderr\fR is not specified, 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 do not normally end with newlines. However, if \fB\-keepnewline\fR is specified then the trailing newline is retained. .PP If standard input is not redirected with .QW < , .QW << or .QW <@ 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 .QW & then the pipeline will be executed in background. 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. The standard output from the last command in the pipeline will go to the application's standard output if it has not 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 .QW glob expansion or other shell-like substitutions are performed on the arguments to commands. .SH "PORTABILITY ISSUES" .TP \fBWindows\fR (all versions) . Reading from or writing to a socket, using the .QW \fB@\0\fIfileId\fR notation, does not work. When reading from a socket, a 16-bit DOS application will hang and a 32-bit application will return immediately with end-of-file. When either type of application writes to a socket, the information is instead sent to the console, if one is present, or is discarded. .RS .PP Note that the current escape resp. quoting of arguments for windows works only with executables using CommandLineToArgv, CRT-library or similar, as well as with the windows batch files (excepting the newline, see below). Although it is the common escape algorithm, but, in fact, the way how the executable parses the command-line (resp. splits it into single arguments) is decisive. .PP Unfortunately, there is currently no way to supply newline character within an argument to the batch files (\fB.cmd\fR or \fB.bat\fR) or to the command processor (\fBcmd.exe /c\fR), because this causes truncation of command-line (also the argument chain) on the first newline character. But it works properly with an executable (using CommandLineToArgv, etc). .PP The Tk console text widget does not provide real standard IO capabilities. Under Tk, when redirecting from standard input, all applications will see an immediate end-of-file; information redirected to standard output or standard error will be discarded. .PP Either forward or backward slashes are accepted as path separators for arguments to Tcl commands. When executing an application, the path name specified for the application may also contain forward or backward slashes as path separators. Bear in mind, however, that most Windows applications accept arguments with forward slashes only as option delimiters and backslashes only in paths. Any arguments to an application that specify a path name with forward slashes will not automatically be converted to use the backslash character. If an argument contains forward slashes as the path separator, it may or may not be recognized as a path name, depending on the program. .PP Additionally, when calling a 16-bit DOS or Windows 3.X application, all path names must use the short, cryptic, path format (e.g., using .QW applba~1.def instead of .QW applbakery.default ), which can be obtained with the .QW "\fBfile attributes\fI fileName \fB\-shortname\fR" command. .PP Two or more forward or backward slashes in a row in a path refer to a network path. For example, a simple concatenation of the root directory \fBc:/\fR with a subdirectory \fB/windows/system\fR will yield \fBc://windows/system\fR (two slashes together), which refers to the mount point called \fBsystem\fR on the machine called \fBwindows\fR (and the \fBc:/\fR is ignored), and is not equivalent to \fBc:/windows/system\fR, which describes a directory on the current computer. The \fBfile join\fR command should be used to concatenate path components. .PP Note that there are two general types of Win32 console applications: .RS .IP [1] CLI \(em CommandLine Interface, simple stdio exchange. \fBnetstat.exe\fR for example. .IP [2] TUI \(em Textmode User Interface, any application that accesses the console API for doing such things as cursor movement, setting text color, detecting key presses and mouse movement, etc. An example would be \fBtelnet.exe\fR from Windows 2000. These types of applications are not common in a windows environment, but do exist. .RE .PP \fBexec\fR will not work well with TUI applications when a console is not present, as is done when launching applications under wish. It is desirable to have console applications hidden and detached. This is a designed-in limitation as \fBexec\fR wants to communicate over pipes. The Expect extension addresses this issue when communicating with a TUI application. .PP When attempting to execute an application, \fBexec\fR first searches for the name as it was specified. Then, in order, \fB.com\fR, \fB.exe\fR, \fB.bat\fR and \fB.cmd\fR are appended to the end of the specified name and it searches for the longer name. If a directory name was not specified as part of the application name, the following directories are automatically searched in order when attempting to locate the application: .IP \(bu 3 The directory from which the Tcl executable was loaded. .IP \(bu 3 The current directory. .IP \(bu 3 The Windows NT 32-bit system directory. .IP \(bu 3 The Windows NT 16-bit system directory. .IP \(bu 3 The Windows NT home directory. .IP \(bu 3 The directories listed in the path. .PP In order to execute shell built-in commands like \fBdir\fR and \fBcopy\fR, the caller must prepend the desired command with .QW "\fBcmd.exe /c\0\fR" because built-in commands are not implemented using executables. .RE .TP \fBUnix\fR (including Mac OS X) . The \fBexec\fR command is fully functional and works as described. .SH "UNIX EXAMPLES" .PP Here are some examples of the use of the \fBexec\fR command on Unix. To execute a simple program and get its result: .PP .CS \fBexec\fR uname -a .CE .SS "WORKING WITH NON-ZERO RESULTS" .PP To execute a program that can return a non-zero result, you should wrap the call to \fBexec\fR in \fBcatch\fR and check the contents of the \fB\-errorcode\fR return option if you have an error: .PP .CS set status 0 if {[catch {\fBexec\fR grep foo bar.txt} results options]} { set details [dict get $options -errorcode] if {[lindex $details 0] eq "CHILDSTATUS"} { set status [lindex $details 2] } else { # Some other error; regenerate it to let caller handle return -options $options -level 0 $results } } .CE .VS 8.6 .PP This is more easily written using the \fBtry\fR command, as that makes it simpler to trap specific types of errors. This is done using code like this: .PP .CS try { set results [\fBexec\fR grep foo bar.txt] set status 0 } trap CHILDSTATUS {results options} { set status [lindex [dict get $options -errorcode] 2] } .CE .VE 8.6 .SS "WORKING WITH QUOTED ARGUMENTS" .PP When translating a command from a Unix shell invocation, care should be taken over the fact that single quote characters have no special significance to Tcl. Thus: .PP .CS awk '{sum += $1} END {print sum}' numbers.list .CE .PP would be translated into something like: .PP .CS \fBexec\fR awk {{sum += $1} END {print sum}} numbers.list .CE .SS "WORKING WITH GLOBBING" .PP If you are converting invocations involving shell globbing, you should remember that Tcl does not handle globbing or expand things into multiple arguments by default. Instead you should write things like this: .PP .CS \fBexec\fR ls -l {*}[glob *.tcl] .CE .SS "WORKING WITH USER-SUPPLIED SHELL SCRIPT FRAGMENTS" .PP One useful technique can be to expose to users of a script the ability to specify a fragment of shell script to execute that will have some data passed in on standard input that was produced by the Tcl program. This is a common technique for using the \fIlpr\fR program for printing. By far the simplest way of doing this is to pass the user's script to the user's shell for processing, as this avoids a lot of complexity with parsing other languages. .PP .CS set lprScript [\fIget from user...\fR] set postscriptData [\fIgenerate somehow...\fR] \fBexec\fR $env(SHELL) -c $lprScript << $postscriptData .CE .SH "WINDOWS EXAMPLES" .PP Here are some examples of the use of the \fBexec\fR command on Windows. To start an instance of \fInotepad\fR editing a file without waiting for the user to finish editing the file: .PP .CS \fBexec\fR notepad myfile.txt & .CE .PP To print a text file using \fInotepad\fR: .PP .CS \fBexec\fR notepad /p myfile.txt .CE .SS "WORKING WITH CONSOLE PROGRAMS" .PP If a program calls other programs, such as is common with compilers, then you may need to resort to batch files to hide the console windows that sometimes pop up: .PP .CS \fBexec\fR cmp.bat somefile.c -o somefile .CE .PP With the file \fIcmp.bat\fR looking something like: .PP .CS @gcc %* .CE or like another variant using single parameters: .CS @gcc %1 %2 %3 %4 %5 %6 %7 %8 %9 .CE .SS "WORKING WITH COMMAND BUILT-INS" .PP Sometimes you need to be careful, as different programs may have the same name and be in the path. It can then happen that typing a command at the DOS prompt finds \fIa different program\fR than the same command run via \fBexec\fR. This is because of the (documented) differences in behaviour between \fBexec\fR and DOS batch files. .PP When in doubt, use the command \fBauto_execok\fR: it will return the complete path to the program as seen by the \fBexec\fR command. This applies especially when you want to run .QW internal commands like \fIdir\fR from a Tcl script (if you just want to list filenames, use the \fBglob\fR command.) To do that, use this: .PP .CS \fBexec\fR {*}[auto_execok dir] *.tcl .CE .SS "WORKING WITH NATIVE FILENAMES" .PP Many programs on Windows require filename arguments to be passed in with backslashes as pathname separators. This is done with the help of the \fBfile nativename\fR command. For example, to make a directory (on NTFS) encrypted so that only the current user can access it requires use of the \fICIPHER\fR command, like this: .PP .CS set secureDir "~/Desktop/Secure Directory" file mkdir $secureDir \fBexec\fR CIPHER /e /s:[file nativename $secureDir] .CE .SH "SEE ALSO" error(3tcl), file(3tcl), open(3tcl) .SH KEYWORDS execute, pipeline, redirection, subprocess '\" Local Variables: '\" mode: nroff '\" End: