1.\" $FreeBSD: src/usr.bin/getopt/getopt.1,v 1.10.2.5 2002/12/29 16:35:39 schweikh Exp $ 2.\" $DragonFly: src/usr.bin/getopt/getopt.1,v 1.5 2008/05/02 02:05:07 swildner Exp $ 3.\" 4.Dd April 3, 1999 5.Dt GETOPT 1 6.Os 7.Sh NAME 8.Nm getopt 9.Nd parse command options 10.Sh SYNOPSIS 11.Nm args=\`getopt Ar optstring $*\` 12; errcode=$?; set \-\- $args 13.Sh DESCRIPTION 14The 15.Nm 16utility is used to break up options in command lines for easy parsing by 17shell procedures, and to check for legal options. 18.Ar Optstring 19is a string of recognized option letters (see 20.Xr getopt 3 ) ; 21if a letter is followed by a colon, the option 22is expected to have an argument which may or may not be 23separated from it by white space. 24The special option 25.Ql \-\- 26is used to delimit the end of the options. 27The 28.Nm 29utility will place 30.Ql \-\- 31in the arguments at the end of the options, 32or recognize it if used explicitly. 33The shell arguments 34(\fB$1 $2\fR ...) are reset so that each option is 35preceded by a 36.Ql \- 37and in its own shell argument; 38each option argument is also in its own shell argument. 39.Sh EXAMPLES 40The following code fragment shows how one might process the arguments 41for a command that can take the options 42.Fl a 43and 44.Fl b , 45and the option 46.Fl o , 47which requires an argument. 48.Bd -literal -offset indent 49args=\`getopt abo: $*\` 50# you should not use \`getopt abo: "$@"\` since that would parse 51# the arguments differently from what the set command below does. 52if [ $? != 0 ] 53then 54 echo 'Usage: ...' 55 exit 2 56fi 57set \-\- $args 58# You cannot use the set command with a backquoted getopt directly, 59# since the exit code from getopt would be shadowed by those of set, 60# which is zero by definition. 61for i 62do 63 case "$i" 64 in 65 \-a|\-b) 66 echo flag $i set; sflags="${i#-}$sflags"; 67 shift;; 68 \-o) 69 echo oarg is "'"$2"'"; oarg="$2"; shift; 70 shift;; 71 \-\-) 72 shift; break;; 73 esac 74done 75echo single-char flags: "'"$sflags"'" 76echo oarg is "'"$oarg"'" 77.Ed 78.Pp 79This code will accept any of the following as equivalent: 80.Bd -literal -offset indent 81cmd \-aoarg file file 82cmd \-a \-o arg file file 83cmd \-oarg -a file file 84cmd \-a \-oarg \-\- file file 85.Ed 86.Sh DIAGNOSTICS 87The 88.Nm 89utility prints an error message on the standard error output and exits with 90status > 0 when it encounters an option letter not included in 91.Ar optstring . 92.Sh SEE ALSO 93.Xr sh 1 , 94.Xr getopt 3 95.Sh HISTORY 96Written by 97.An Henry Spencer , 98working from a Bell Labs manual page. 99Behavior believed identical to the Bell version. 100Example changed in 101.Fx 102version 3.2 and 4.0. 103.Sh BUGS 104Whatever 105.Xr getopt 3 106has. 107.Pp 108Arguments containing white space or embedded shell metacharacters 109generally will not survive intact; this looks easy to fix but 110isn't. People trying to fix 111.Nm 112or the example in this manpage should check the history of this file 113in 114.Fx . 115.Pp 116The error message for an invalid option is identified as coming 117from 118.Nm 119rather than from the shell procedure containing the invocation 120of 121.Nm ; 122this again is hard to fix. 123.Pp 124The precise best way to use the 125.Nm set 126command to set the arguments without disrupting the value(s) of 127shell options varies from one shell version to another. 128.Pp 129Each shellscript has to carry complex code to parse arguments halfway 130correctly (like the example presented here). A better getopt-like tool 131would move much of the complexity into the tool and keep the client 132shell scripts simpler. 133