check if file is empty

stolz · #1 (**permalink**) 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 (**permalink**) 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 (**permalink**) 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 (**permalink**) 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 (**permalink**) 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 (**permalink**) 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.

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
How to check for empty file in Perl?	deepakwins	UNIX for Dummies Questions & Answers	1	03-04-2008 03:00 PM
Check for empty string	rahman_riyaz	Shell Programming and Scripting	12	01-24-2008 03:13 AM
Check for Empty Command Argument	Nysif Steve	UNIX for Dummies Questions & Answers	6	09-19-2007 03:59 PM
How to check for null or empty string	doer	Shell Programming and Scripting	5	07-24-2007 01:31 AM
How can I make the for command check to see if a file is empty before executing?	chrchcol	Shell Programming and Scripting	3	07-29-2006 03:14 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode	Rate This Thread:


	Powered by