Visit Our UNIX and Linux User Community

Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

getopt(1) [freebsd man page]

GETOPT(1)						    BSD General Commands Manual 						 GETOPT(1)

NAME
getopt -- parse command options SYNOPSIS
args=`getopt optstring $*` ; errcode=$?; set -- $args DESCRIPTION
The getopt utility is used to break up options in command lines for easy parsing by shell procedures, and to check for legal options. Optstring is a string of recognized option letters (see getopt(3)); if a letter is followed by a colon, the option is expected to have an argument which may or may not be separated from it by white space. The special option '--' is used to delimit the end of the options. The getopt utility will place '--' in the arguments at the end of the options, or recognize it if used explicitly. The shell arguments ($1 $2 ...) are reset so that each option is preceded by a '-' and in its own shell argument; each option argument is also in its own shell argu- ment. EXIT STATUS
The getopt utility prints an error message on the standard error output and exits with status > 0 when it encounters an option letter not included in optstring. EXAMPLES
The following code fragment shows how one might process the arguments for a command that can take the options -a and -b, and the option -o, which requires an argument. args=`getopt abo: $*` # you should not use `getopt abo: "$@"` since that would parse # the arguments differently from what the set command below does. if [ $? -ne 0 ]; then echo 'Usage: ...' exit 2 fi set -- $args # You cannot use the set command with a backquoted getopt directly, # since the exit code from getopt would be shadowed by those of set, # which is zero by definition. while true; do case "$1" in -a|-b) echo "flag $1 set"; sflags="${1#-}$sflags" shift ;; -o) echo "oarg is '$2'"; oarg="$2" shift; shift ;; --) shift; break ;; esac done echo "single-char flags: '$sflags'" echo "oarg is '$oarg'" This code will accept any of the following as equivalent: cmd -aoarg file file cmd -a -o arg file file cmd -oarg -a file file cmd -a -oarg -- file file SEE ALSO
getopts(1), sh(1), getopt(3) HISTORY
Written by Henry Spencer, working from a Bell Labs manual page. Behavior believed identical to the Bell version. Example changed in FreeBSD version 3.2 and 4.0. BUGS
Whatever getopt(3) has. Arguments containing white space or embedded shell metacharacters generally will not survive intact; this looks easy to fix but is not. Peo- ple trying to fix getopt or the example in this manpage should check the history of this file in FreeBSD. The error message for an invalid option is identified as coming from getopt rather than from the shell procedure containing the invocation of getopt; this again is hard to fix. The precise best way to use the set command to set the arguments without disrupting the value(s) of shell options varies from one shell ver- sion to another. Each shellscript has to carry complex code to parse arguments halfway correctly (like the example presented here). A better getopt-like tool would move much of the complexity into the tool and keep the client shell scripts simpler. BSD
January 26, 2011 BSD

Check Out this Related Man Page

getoptcvt(1)							   User Commands						      getoptcvt(1)

NAME
getoptcvt - convert to getopts to parse command options SYNOPSIS
/usr/lib/getoptcvt [-b] filename /usr/lib/getoptcvt DESCRIPTION
/usr/lib/getoptcvt reads the shell script in filename, converts it to use getopts instead of getopt, and writes the results on the standard output. getopts is a built-in Bourne shell command used to parse positional parameters and to check for valid options. See sh(1). It supports all applicable rules of the command syntax standard (see Rules 3-10, intro(1)). It should be used in place of the getopt command. (See the NOTES section below.) The syntax for the shell's built-in getopts command is: getopts optstring name [ argument...] optstring must contain the option letters the command using getopts will recognize; if a letter is followed by a colon (:), the option is expected to have an argument, or group of arguments, which must be separated from it by white space. Each time it is invoked, getopts places the next option in the shell variable name and the index of the next argument to be processed in the shell variable OPTIND. Whenever the shell or a shell script is invoked, OPTIND is initialized to 1. When an option requires an option-argument, getopts places it in the shell variable OPTARG. If an illegal option is encountered, ? will be placed in name. When the end of options is encountered, getopts exits with a non-zero exit status. The special option -- may be used to delimit the end of the options. By default, getopts parses the positional parameters. If extra arguments (argument ...) are given on the getopts command line, getopts parses them instead. So that all new commands will adhere to the command syntax standard described in intro(1), they should use getopts or getopt to parse posi- tional parameters and check for options that are valid for that command (see the NOTES section below). OPTIONS
The following option is supported: -b Makes the converted script portable to earlier releases of the UNIX system. /usr/lib/getoptcvt modifies the shell script in file- name so that when the resulting shell script is executed, it determines at run time whether to invoke getopts or getopt. EXAMPLES
Example 1: Processing the arguments for a command The following fragment of a shell program shows how one might process the arguments for a command that can take the options -a or -b, as well as the option -o, which requires an option-argument: while getopts abo: c do case $c in a | b) FLAG=$c;; o) OARG=$OPTARG;; ?) echo $USAGE exit 2;; esac done shift `expr $OPTIND - 1` Example 2: Equivalent code expressions This code accepts any of the following as equivalent: cmd -a -b -o "xxx z yy" filename cmd -a -b -o "xxx z yy" -filename cmd -ab -o xxx,z,yy filename cmd -ab -o "xxx z yy" filename cmd -o xxx,z,yy b a filename ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of getopts: LC_CTYPE, LC_MESSAGES, and NLSPATH. OPTIND This variable is used by getoptcvt as the index of the next argument to be processed. OPTARG This variable is used by getoptcvt to store the argument if an option is using arguments. EXIT STATUS
The following exit values are returned: 0 An option, specified or unspecified by optstring, was found. >0 The end of options was encountered or an error occurred. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ |CSI |enabled | +-----------------------------+-----------------------------+ SEE ALSO
intro(1), getopts(1), sh(1), shell_builtins(1), getopt(3C), attributes(5) DIAGNOSTICS
getopts prints an error message on the standard error when it encounters an option letter not included in optstring. NOTES
Although the following command syntax rule (see intro(1)) relaxations are permitted under the current implementation, they should not be used because they may not be supported in future releases of the system. As in the EXAMPLES section above, -a and -b are options, and the option -o requires an option-argument. The following example violates Rule 5: options with option-arguments must not be grouped with other options: example% cmd -aboxxx filename The following example violates Rule 6: there must be white space after an option that takes an option-argument: example% cmd -ab oxxx filename Changing the value of the shell variable OPTIND or parsing different sets of arguments may lead to unexpected results. SunOS 5.10 7 Jan 2000 getoptcvt(1)

Featured Tech Videos