elif won't work!

[marcmc]

I have a redhat bash script and the elif will not work. Any ideas?
At marc4 the $v_countRpts val is 0 and so is the $v_return_ssh value, but the code will alway enter the elif block, i cannot see why.

echo "marc4"
echo "$v_countRpts"
echo "$v_return_ssh"

if [ $v_return_ssh = 1 ]
then

echo "marc5"
echo "$v_countRpts"
echo "$v_return_ssh"

i=`expr $file_length + 1`
echo "#### Exiting batch call loop due to error in ${bat_file} "
return 1
elif [ $v_return_ssh = 0 ] && [ $v_countRpts > 0 ]
then
# poll the same schedule again if not ready.
i=`expr $i + 0`
m=`expr $m + 1`
echo "marc6"
echo "$v_countRpts"
echo "$v_return_ssh"
else
echo "marc7"
echo "$v_countRpts"
echo "$v_return_ssh"
# poll the next schedule.
i=`expr $i + 1`
m=`expr $m + 1`
fi
else
echo "marc8"
echo "$v_countRpts"
echo "$v_return_ssh"
# poll the next flexi schedule.
i=`expr $i + 1`
m=`expr $m + 1`
fi

[wje_lf]

Suggestion:

Whip up the simplest five-liner script possible which uses elif, and see whether it works.

If it works, then take a debug copy of your longer script and start removing stuff until it looks like the simple five-liner. Along the way, it should start working. What you had to remove to get it to work will be your clue.

If it doesn't work, post the simple five-liner here.

[marcmc]

I got it by simly adding '-gt' instead of '>' in the elif statement! I am very new to Linux and don;t quite know the standard. For any of the tests above I also added '==' instead of '=' as I don't know the 'formal' approach. Are there any guidelines as there is a mixture of ==, =, >, 'gt etc etc in this script.

[Franklin52]

Escape the ">" in the elif statement:

elif [ $v_return_ssh = 0 ] && [ $v_countRpts \> 0 ]

Regards

[Franklin52]

I got it by simly adding '-gt' instead of '>' in the elif statement! I am very new to Linux and don;t quite know the standard.

You have a point on this, I may refer to this document:

http://tldp.org/LDP/abs/html/comparison-ops.html

Regards

[drl]

Hi.

The double-bracket syntax effectively quotes the ">" symbol. The single-bracket causes a file to be created:

#!/bin/bash -

# @(#) s1       Demonstrate arithmetic comparison, quoting within [[ ]].

echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version =o $(_eat $0 $1)

a=1
b=2

rm -f 2
set -o noclobber
touch 2

echo
echo " Double brackets:"
if [[ $a > $b ]]
then
  echo " Value $a is greater than $b."
else
  echo " Value $b is greater than $a."
fi

echo
echo " Single brackets with -gt:"
if [ $a -gt $b ]
then
  echo " Value $a is greater than $b."
else
  echo " Value $b is greater than $a."
fi

echo
echo " Single brackets with >:"
if [ $a > $b ]
then
  echo " Value $a is greater than $b."
else
  echo " Value $b is greater than $a."
fi

exit 0

Producing:

% ./s1
(Versions displayed with local utility "version")
Linux 2.6.11-x1
GNU bash 2.05b.0

 Double brackets:
 Value 2 is greater than 1.

 Single brackets with -gt:
 Value 2 is greater than 1.

 Single brackets with >:
./s1: line 35: 2: cannot overwrite existing file
 Value 2 is greater than 1.

The double-bracket syntax has other advantages, but this one seems very useful in contexts such as this ... cheers, drl

[marcmc]

thanks all, can you recommend a linux book(covering starter to advanced) but something with very easy to follow and find references please.

[Franklin52]

There are also excellent online tutorials, just Google for "bash tutorial", 2 links:

BASH Programming - Introduction HOW-TO

http://tldp.org/LDP/abs/html/


Regards