arguments expected error

Shell Programming and Scripting
1

ive implemented getopt for the command line but have this problem,

#!/bin/sh
text=""
set -- getopt "t" etc ....    #sets arguments
while :
do
   case "$1" in                  #gets arguments
   -t: shift; text="$1" ;;
   shift
done
shift

if [ $text = "" ]
then
   echo "no text"
else
   echo "text"
fi

when i run the program ./script -t <text>
it prints "text"
but when i just run ./script
it returns a "arguments expected" message, (shouldnt it return "no text" ?)
is there a way to fix this, i want to be able to run ./script without it complaining as well as ./script -t <text>

2

Two things that came to my notice.

Since you are using case statements, you should close the case statements with esac

Your script would now look like this:

do
   case "$1" in                  #gets arguments
   -t: shift; text="$1" ;;
   esac
done

Regarding your use of shift indicates that the script requires you to input arguments. From the man pages we have the following:

 shift [n]
              The  positional  parameters  from n+1 ... are renamed to $1 ....
              Parameters represented by the numbers  $#  down  to  $#-n+1  are
              unset.   n  must  be a non-negative number less than or equal to
              $#.  If n is 0, no parameters are changed.  If n is  not  given,
              it  is assumed to be 1.  If n is greater than $#, the positional
              parameters are not changed.  The return status is  greater  than
              zero if n is greater than $# or less than zero; otherwise 0.

Also your sciprt has a $1 which actually in scipt-terminology refers to the first argument.

No arguments + your script = "arguments expected"

It is always a good idea to check whether the user has provided any arguments at all.

$# gives you the count of the number of arguments provided at command line.

You script should be tweaked like this:

#! /bin/sh

if [ $# -eq 0 ] ; then
   echo "No text"
else
while :
do
   case "$1" in                  #gets arguments
   -t: shift; text="$1" ;;
   shift
done
shift
   echo "Text"
fi
3

thanks for that, that was quite informative.
just wandering how would that script be modified if say there
were multiple arguments?
e.g
arguments "t:w"
if theres no -t
do something
else
do something else
if theres no -w
do something
else
do something else
etc ...

4

Check out this thread..

It could be of help to you.

Vino

5

thanks for that, it does help.