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.TH GETFLAGS 8
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.SH NAME
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getflags, usage \- command-line parsing for shell scripts
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.SH SYNOPSIS
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.B aux/getflags $*
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.PP
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.B aux/usage
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.SH DESCRIPTION
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.I Getflags
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parses the options in its command-line arguments
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according to the environment variable
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.BR $flagfmt .
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This variable should be a list of comma-separated options.
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Each option can be a single letter, indicating that it does
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not take arguments, or a letter followed by the space-separated
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names of its arguments.
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.I Getflags
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prints an
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.IR rc (1)
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script on standard output which initializes the
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environment variable
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.BI $flag x
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for every option mentioned in
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.BR $flagfmt .
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If the option is not present on the command-line, the script
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sets that option's flag variable to an empty list.
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Otherwise, the script sets that option's flag variable with
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a list containing the option's arguments or,
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if the option takes no arguments,
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with the string
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.BR 1 .
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The script also sets the variable
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.B $*
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to the list of arguments following the options.
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The final line in the script sets the
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.B $status
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variable, to the empty string on success
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and to the string
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.B usage
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when there is an error parsing the command line.
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.PP
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.I Usage
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prints a usage message to standard error.
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It creates the message using
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.BR $flagfmt ,
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as described above,
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.BR $args ,
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which should contain the string to be printed explaining
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non-option arguments,
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and
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.BR $0 ,
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the program name
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(see
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.IR rc (1)).
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.SH EXAMPLE
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Parse the arguments for
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.IR leak (1):
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.IP
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.EX
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flagfmt='b,s,f binary,r res,x width'
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args='name | pid list'
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if(! ifs=() eval `{aux/getflags $*} || ~ $#* 0){
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	aux/usage
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	exit usage
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}
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.EE
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.SH SOURCE
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.B /sys/src/cmd/aux/getflags.c
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.br
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.B /sys/src/cmd/aux/usage.c
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.SH SEE ALSO
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.IR arg (2)