echo $1
echo $2
#opt is the variable where we are storing the option value through getops
echo $opt
output should be
Code:
par1
par2
option1
This is needed because we already have a system which uses only parameters. Now the last parameter is optional. So It's hard to add extra optional parameter.
Also changing the current parameter to all option is not recommended because the client does not want to change all the existing cron entries fearing high risk in production.
#!/bin/bash
while getopts ":s:" opt; do
case $opt in
s ) opt1="`echo $OPTARG| sed 's/^ *//'`" ;;
esac
done
echo "opt1= $opt1"
echo "1st par: $1"
echo "2nd par: $2"
The standards specify that options should come before operands; not after. There are ways to work around that, but I don't see any real reason to bend the guidelines for what you're trying to do. There are a couple of easy ways to deal with this. I've included sample code below for both of these.
The 1st way uses getopts the way it was intended and would be described in UNIX-like man pages with the SYNOPIS:
Code:
test1 [-s opt_val] parm1 parm2
When using this form, the script requires two operands (parm1 and parm2) and accepts an option which can either be specified as a single command-line argument (-sopt_val) as as two command-line arguments (-s opt_val). In either case, if opt_val contains multiple words, the whitespace between words can be escape or quoted. If parm1 happens to start with a minus sign (-), getopts will accept an operand of -- to indicate end-of-options.
A sample bash (this will also work with any other POSIX conforming shell such as ksh) script for this method is:
Code:
#!/bin/bash
# FIRST EXAMPLE: SYNOPSIS: test1 [-s opt_val] parm1 parm2
# Initialize script variables
IAm=${0##/} # Last component of this script's pathname
Usage="Usage: %s [-s opt_val] parm1 parm2\n" # Usage message format string
sopt="None" # -s option option argument default value
# Parse command line arguments:
# Process options:
while getopts "s:" opt
do case $opt in
# Note that with getopts, the -s option and its option argument can be
# specified as two arguments (-s opt_val) or as one argument
# (-sopt_val) and the single line of code below will properly handle
# either case.
(s) sopt=$OPTARG;;
(*) printf "$Usage" "$IAm" >&2
exit 1;;
esac
done
shift $((OPTIND - 1))
# Process operands:
if [ $# -ne 2 ]
then printf "%s: Expected 2 operands, found %d\n" "$IAm" $#
printf "$Usage" "$IAm" >&2
exit 2
fi
# Display values parsed from the command line:
echo "s option option-argument: $sopt"
echo "1st par: $1"
echo "2nd par: $2"
Sample commands and corresponding output for this form follow:
The 2nd way does not use getopts, but instead just uses $# to determine how many command-line arguments are present. Again it always requires two operands, but this one accepts (but does not require) one more operand and would be described in UNIX-like man pages with the synopsis:
Code:
test2 parm1 parm2 [opt_param]
A sample bash script (that, again, will work with any POSIX conforming shell) for this method is:
Code:
#!/bin/bash
# SECOND EXAMPLE: SYNOPSIS: test2 parm1 parm2 [opt_param]
# Initialize script variables
IAm=${0##/} # Last component of this script's pathname
Usage="Usage: %s parm1 parm2 [opt_param]\n" # Usage message format string
opt_parm=${3:-None} # opt_parm 3rd operand: "None" if not on command line
# Process operands:
if [ $# -lt 2 ] || [ $# -gt 3 ]
then printf "%s: Expected 2 or 3 operands, found %d\n" "$IAm" $#
printf "$Usage" "$IAm" >&2
exit 2
fi
# Display values parsed from the command line:
echo "optional parameter: $opt_parm"
echo "1st par: $1"
echo "2nd par: $2"
Sample commands and corresponding output for this form follow:
Code:
test2 1 2 3 4
produces:
Code:
test2: Expected 2 or 3 operands, found 4
Usage: test2 parm1 parm2 [opt_param]
Both of these scripts set the default value for the optional value to "None". It is clear visually for these examples. Depending on how you want to use this optional value, an empty string (or any other string you want) may be more appropriate.
Note that both of these sample scripts redirect all diagnostic messages to stderr (rather than stdout). And, if and only if a diagnostic message is written, the exit status will be non-zero.
Note also that even if a script does not (currently) accept options, it is still a good idea to include comehting like:
Code:
while getopts "" opt
do case $opt in
(*) printf "$Usage" "${0##*/}" >&2
exit 1;;
esac
done
shift $((OPTIND - 1))
So a user can always issue the command:
Code:
scriptname "-?"
to get a synopsis for the utility including a list of the currently accepted options, and can use:
Code:
scriptname -- operands
to protect itself in csae the 1st operand might start with a minus sign that should not be interpreted as the start of an option string.
Hope this helps...
This User Gave Thanks to Don Cragun For This Post:
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