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String comparison using bash

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# 1  
Old 05-11-2010
String comparison using bash
I have a program to create a directory if not present. Here is the program.

FYI: Directory name format: YYYY_MM_DD

Code:
#!/bin/bash
date=`date +%Y_%m_%d`
presence=$(ls -lrt /TS_File/ | grep "$date" | awk '{print $9}')
if [ $date != $presence ]
then
        mkdir /TS_File/$date
else
        echo "Unable to Create a Directory"
fi

Output:
Code:
./date.sh: line 4: [: 2010_05_11: unary operator expected
Unable to Create a Directory

Please help me to recover from this error and need a solve my purpose.


Moderator's Comments:
Mod Comment Please use code tags
Last edited by Franklin52; 05-11-2010 at 01:21 PM..
# 2  
Old 05-11-2010
Try this...

Code:
#!/bin/bash
today=`date +%Y_%m_%d`
if [ ! -d /TS_File/${today} ]; then
    mkdir /TS_File/${today}
fi

Last edited by dunkar70; 05-11-2010 at 12:16 PM.. Reason: Corrected typo
# 3  
Old 05-11-2010
Code:
#!/bin/bash
fname=$(date +%Y_%m_%d)
[[ -d /TS_file/${fname} ]] || mkdir /TS_file/${fname}

You cannot use the word date for a variable name. It is a command.
# 4  
Old 05-11-2010
Why not? This isn't VB, where 'magic' variable names may mysteriously reset your system clock...

Code:
$ date=$(date)
$ echo ${date}
Tue May 11 09:45:49 CST 2010

...not that it's a good idea. Best to avoid confusion and not have multiple meanings for names.
# 5  
Old 05-11-2010
Thanks Dunkar70. Your code worked for me.
# 6  
Old 05-12-2010
Quote:
Originally Posted by jim mcnamara
Code:
#!/bin/bash
fname=$(date +%Y_%m_%d)
[[ -d /TS_file/${fname} ]] || mkdir /TS_file/${fname}

You cannot use the word date for a variable name. It is a command.

Of course you can. You can even use shell keywords and builtin commands:
Code:
if=1
do=42
cd=whatever

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