Usage of optarg

Shell Programming and Scripting
1

Hello Friends,

I need to pass arguments to a shell scripts. but for this i need to take the arguments only if they are supplied to the script as arguments.

Like :

Prompt > scriptname -d device_cd -s message

so how do i capture these arguments ?> i think we have to use optarg.but i dont know exact usage.

Can any one please help?

Thanks in advance
Veera

2

try getopts in some kind of a loop
example:

function Parse
{
   while getopts :r:l:p:o:q:t: name
   do
     case $name in
        l) LOG="$OPTARG" ;;        # LOG FILE
        p) PROC="$OPTARG" ;;       # Process name
        o) ONE_UP="$OPTARG" ;;     # One_Up Number
        q) PRNT="$OPTARG" ;;       # q Print queue 'FTP' for now
        r) LIS="$OPTARG" ;;        # lis file name
        t) FTPDEST="$OPTARG" ;;     # D = Disk, T = Tape
        *) Usage ;;                     # display usage and exit
     esac
   done
3

Hi Jim mcnamara,

This helps. Thanks for the response.
bye
Veera

4

Hi Jim mcnamara and friends,
I used getopts in the way you suggested. But what if i have to send two mandatory arguments to the script and the rest two as optional parameters ?
i have having problem in giving both Mandatory and optional fields at the same time to the script.
Please help.
Thanks in advance
Veera

5

In Jim's example, he's setting variables; therefore, he could test the variables with [ -z "${VAR...}" ] and create appropriate exceptions if they aren't defined.

function Parse
{
   while getopts :r:l:p:o:q:t: name
   do
     case $name in
        l) LOG="$OPTARG" ;;        # LOG FILE
        p) PROC="$OPTARG" ;;       # Process name
        o) ONE_UP="$OPTARG" ;;     # One_Up Number
        q) PRNT="$OPTARG" ;;       # q Print queue 'FTP' for now
        r) LIS="$OPTARG" ;;        # lis file name
        t) FTPDEST="$OPTARG" ;;     # D = Disk, T = Tape
        *) Usage ;;                     # display usage and exit
     esac
   done
   [ -z "${PROC}" -o -z "${PRNT}" ] && Usage
6

You can take this a step further by using a check sum. Say you have 5 or 10 required flags, you could accomplish this by keeping track of those arguments you have already processed by using a counter. Check the value of the counter at the end to verify all flags were received.

USAGE="Usage: `basename $0` [-s schemaname] [-d databasename] [-u username] -f -t -h"
while getopts :s:d:u:fth params
do
   case $params in
     s) SOURCESCHEMA="$OPTARG"
        let COUNT= $COUNT+10000
         ;;
     f) FULL='y'
         ;;

     t) TABLE='y'
         ;;

     d) DBNAME="$OPTARG"
         let COUNT= $COUNT+1
        ;;

     u) USERNAME="$OPTARG"
         let COUNT= $COUNT+1000
         ;;
     h) 
         help_doc
         exit 0 
         ;;
     ?) 
         echo "Invalid Option Specified"
         echo "$USAGE" 1>&2 ; exit 1 
         ;;
   esac

if [ "$COUNT" -ne 10101 ]
  then
    help_doc
    exit 0
elif [ ! -z $FULL ]
   then
      echo "Paramater FULL is Set"
elif [ ! -z $TABLE ]
   then
      echo "Paramater TABLE is Set"
else
    echo "Neither TABLE or FULL Are Set"
fi