code / arg

   1 .\" Manpage for arg.
   2 .\" Contact bruce@bruce-hill.com to correct errors or typos.
   3 .TH man 8 "14 February 2019" "1.0" "arg man page"
   4 .SH NAME
   5 arg \- A minimalist command line argument parser
   6 .SH SYNOPSIS
   7 .B arg
   8 .I flag
   9 .I ...
  10 .SH DESCRIPTION
  11 This is a handy tool for parsing out a single argument from a list of command
  12 line arguments.
  13 
  14 .SH INPUT
  15 The first argument must be a flag (for example \fB-f\fR, \fB--foo\fR, or
  16 \fBfoo\fR). This flag will be searched for among the remaining arguments.
  17 
  18 .SH OUTPUT AND RETURN
  19 If the flag is found, the program will exit successfully (exit status 0),
  20 otherwise the program will fail (exit status 1). A flag is found if:
  21 
  22 .RS 4
  23 .HP 2
  24 \fB-\fR one of the extra arguments is an exact match:
  25 \fBarg --foo .. \fI--foo\fB [<value>]\fR
  26 
  27 .HP 2
  28 \fB-\fR one of the exact arguments begins with the flag followed by an '=' sign:
  29 \fBarg --foo .. \fI--foo=\fB[<value>]\fR
  30 
  31 .HP 2
  32 \fB-\fR or the flag is a single dash followed by a single letter, and the letter
  33 is found clustered with other letters after a single dash:
  34 \fBarg -f .. -x\fIf\fBy\fR
  35 
  36 If a value is found, the value is printed to stdout.
  37 
  38 .RE
  39 
  40 .SH EXAMPLES
  41 The primary use case of this program is for shell scripting, as a much simpler
  42 and easier to use alternative to getopt. Here are some simple shell script
  43 examples:
  44 
  45 .TP
  46 .B
  47 if foo=`arg --foo "$@"`; then echo "foo is '$foo'"; fi
  48 If \fI--foo=value\fR or \fI--foo value\fR are in the arguments, the shell script
  49 will print "foo is 'value'".
  50 
  51 Note: it is important to put quotes around \fB$@\fR to ensure that
  52 arguments with spaces get passed correctly.
  53 
  54 .TP
  55 .B
  56 if arg -v "$@" || arg --verbose "$@"; then echo "Verbose!"; fi
  57 Prints "Verbose!" if the shell script was run with either \fI-v\fR or \fI--verbose\fR.
  58 
  59 .TP
  60 .B
  61 prefix=`arg prefix "$@" || echo "/usr/local"`
  62 Sets prefix to the value of the \fIprefix\fR flag the user pased in, or if
  63 no such flag was passed, \fI/usr/local\fR.
  64 
  65 .SH AUTHOR
  66 Bruce Hill (bruce@bruce-hill.com)