check if file is empty - Shell Programming and Scripting

stolz · #1 09-24-2005

How do I check if a file is empty in a sh script

I want to test in my shell script if the output file is empty and if it is do one thing and if it isnt empty do another?

any ideas?

vino · #2 09-24-2005

Read the man pages of test

Code:

       -s FILE
              FILE exists and has a size greater than zero

Within a script it would take this form.

Code:

#! /bin/ksh

if [[ -s $FILE ]] ; then
echo "$FILE has data."
else
echo "$FILE is empty."
fi ;

vino

zazzybob · #3 09-24-2005

Quote:

Originally Posted by vino

Code:

#! /bin/ksh

if [[ -s $FILE ]] ; then
echo "$FILE has data."
else
echo "$FILE is empty."
fi ;

vino

an exit status of 1 indicates that the FILE is empty or the file does not exist.....

Code:

$ ls
$ touch file_1
$ dd if=/dev/zero of=$HOME/tmp/file_2 bs=1 count=100
100+0 records in
100+0 records out
$ ls -l file_1 file_2 file_3
ls: file_3: No such file or directory
-rw-rw-r--  1 foo bar   0 Sep 24 20:28 file_1
-rw-rw-r--  1 foo bar 100 Sep 24 20:28 file_2
$ [[ -s file_1 ]]
$ echo $?
1
$ [[ -s file_2 ]]
$ echo $?
0
$ [[ -s file_3 ]]
$ echo $?
1

Cheers
ZB

vino · #4 09-24-2005

Quote:

Originally Posted by zazzybob

an exit status of 1 indicates that the FILE is empty or the file does not exist.....

Code:

$ ls -l file_1 file_2 file_3
ls: file_3: No such file or directory
-rw-rw-r--  1 foo bar   0 Sep 24 20:28 file_1
-rw-rw-r--  1 foo bar 100 Sep 24 20:28 file_2
$ [[ -s file_1 ]]
$ echo $?
1
$ [[ -s file_2 ]]
$ echo $?
0
$ [[ -s file_3 ]]
$ echo $?
1

Cheers
ZB

A sleek 'n' smart solution !!

matrixmadhan · #5 09-24-2005

this is just another way of doing it

a round about one

Code:

if [ `ls -l <file> | awk '{print $5}'` -eq 0 ]
then
//condition for being empty
else
//condition for not being empty
fi

better way of doing is using the -s option of test

stolz · #6 09-27-2005

All worked as I required -s FILE option was the solution I used in my script and now I am a happy man.

lapisguy · #7 07-24-2007

I have a requirement where if file size is 487 then ignore it otherwise put into e-mail script? I can do it using -s but it does only if file is empty...
any clue on this please???

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