1.\" $FreeBSD$ 2.\" 3.Dd April 3, 1999 4.Dt GETOPT 1 5.Os 6.Sh NAME 7.Nm getopt 8.Nd parse command options 9.Sh SYNOPSIS 10.Nm args=\`getopt Ar optstring $*\` 11; errcode=$?; set \-\- $args 12.Sh DESCRIPTION 13The 14.Nm 15utility is used to break up options in command lines for easy parsing by 16shell procedures, and to check for legal options. 17.Ar Optstring 18is a string of recognized option letters (see 19.Xr getopt 3 ) ; 20if a letter is followed by a colon, the option 21is expected to have an argument which may or may not be 22separated from it by white space. 23The special option 24.Ql \-\- 25is used to delimit the end of the options. 26The 27.Nm 28utility will place 29.Ql \-\- 30in the arguments at the end of the options, 31or recognize it if used explicitly. 32The shell arguments 33(\fB$1 $2\fR ...) are reset so that each option is 34preceded by a 35.Ql \- 36and in its own shell argument; 37each option argument is also in its own shell argument. 38.Sh EXIT STATUS 39The 40.Nm 41utility prints an error message on the standard error output and exits with 42status > 0 when it encounters an option letter not included in 43.Ar optstring . 44.Sh EXAMPLES 45The following code fragment shows how one might process the arguments 46for a command that can take the options 47.Fl a 48and 49.Fl b , 50and the option 51.Fl o , 52which requires an argument. 53.Pp 54.Bd -literal -offset indent 55args=\`getopt abo: $*\` 56# you should not use \`getopt abo: "$@"\` since that would parse 57# the arguments differently from what the set command below does. 58if [ $? -ne 0 ] 59then 60 echo 'Usage: ...' 61 exit 2 62fi 63set \-\- $args 64# You cannot use the set command with a backquoted getopt directly, 65# since the exit code from getopt would be shadowed by those of set, 66# which is zero by definition. 67for i 68do 69 case "$i" 70 in 71 \-a|\-b) 72 echo flag $i set; sflags="${i#-}$sflags"; 73 shift;; 74 \-o) 75 echo oarg is "'"$2"'"; oarg="$2"; shift; 76 shift;; 77 \-\-) 78 shift; break;; 79 esac 80done 81echo single-char flags: "'"$sflags"'" 82echo oarg is "'"$oarg"'" 83.Ed 84.Pp 85This code will accept any of the following as equivalent: 86.Pp 87.Bd -literal -offset indent 88cmd \-aoarg file file 89cmd \-a \-o arg file file 90cmd \-oarg -a file file 91cmd \-a \-oarg \-\- file file 92.Ed 93.Sh SEE ALSO 94.Xr getopts 1 , 95.Xr sh 1 , 96.Xr getopt 3 97.Sh HISTORY 98Written by 99.An Henry Spencer , 100working from a Bell Labs manual page. 101Behavior believed identical to the Bell version. 102Example changed in 103.Fx 104version 3.2 and 4.0. 105.Sh BUGS 106Whatever 107.Xr getopt 3 108has. 109.Pp 110Arguments containing white space or embedded shell metacharacters 111generally will not survive intact; this looks easy to fix but 112is not. 113People trying to fix 114.Nm 115or the example in this manpage should check the history of this file 116in 117.Fx . 118.Pp 119The error message for an invalid option is identified as coming 120from 121.Nm 122rather than from the shell procedure containing the invocation 123of 124.Nm ; 125this again is hard to fix. 126.Pp 127The precise best way to use the 128.Nm set 129command to set the arguments without disrupting the value(s) of 130shell options varies from one shell version to another. 131.Pp 132Each shellscript has to carry complex code to parse arguments halfway 133correctly (like the example presented here). 134A better getopt-like tool 135would move much of the complexity into the tool and keep the client 136shell scripts simpler. 137