ccf5d3fb9d
This makes the flagfmt parser more robust and accepting a looser input language — namely by allowing whitespace around specifier fields and ignoring any empty fields. Long flagfmts can thus be pleasingly displayed: flagfmt=' a, b, c, C:cache, m:mtpt mountpoint, s:srvn srvname'
108 lines
2.4 KiB
Text
108 lines
2.4 KiB
Text
.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 flags 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 comma-separated list of flag specifiers.
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Each flag is a single letter, optionally followed by a
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colon and a name. It may be followed by a space-separated
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list of argument names.
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.PP
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.I Getflags
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prints an
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.IR rc (1)
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script to be evaluated by the calling program.
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For every flag specified in
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.BR $flagfmt ,
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the generated script sets a corresponding environment variable.
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If the flag specifier contains
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.BR :name ,
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the corresponding variable is named
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.BR $name .
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Otherwise, it is named
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.BI $flag x.
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.PP
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After evaluating the script, the environment variables will
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be set as follows:
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If a flag is not present in the argument list, the environment
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variable will default to the empty list.
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If the flag is present and takes no arguments, the environment
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variable will be initialized with the string
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.BR '1' .
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If the flag takes arguments, the flag's variable will be initialized
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with a list of those argument values.
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The script then sets the variable
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.B $*
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to the list of remaining non-flag arguments.
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.PP
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The
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.B $status
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is variable to the empty string on success, or
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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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The message is constructed using
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.BR $0 ,
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.BR $flagfmt ,
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and
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.BR $args .
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The program name is taken from
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.BR $0 ,
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as set by
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.IR rc (1)
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The list of flags is extracted from
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.BR $flagfmt .
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The description of positional argument list is taken from
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.BR $args .
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.SH EXAMPLE
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.PP
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An example of the script generated:
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.IP
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.EX
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% flagfmt='e:example, x, a:arg with args'
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% aux/getflags -exa arg list positional stuff
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example=()
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flagx=()
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arg=()
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example=1
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flagx=1
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arg=(arg list)
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*=(positional stuff)
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status=''
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.EE
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.PP
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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:showbmp, s:acidfmt, 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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if(~ $#showbmp 0)
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echo '-b flag not set'
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echo $showbmp # named
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echo $acidfmt # also named
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echo $flagf # default name
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echo $flagr # default name
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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)
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