simple bash question

[fugtruck]

I want to search a text file for the existence of certain strings and execute a command if they exist, something along the lines of:

if <string> exists
command

or

if <any member of this list exists>
command

Any suggestions? I know how to manually search a file with grep, cat, etc., but the "if this exists" part eludes me.

 

[jaxtell]

I'm no bash expert, but I think this'll do.

#!/bin/bash
COUNT=`grep -c "php" test.php`
if [ $COUNT != 0 ]
then
echo "do something"
else
echo "do something else"
fi

-----------------------------------------
I cannot be bought. Find leasing information at

http://www.joshaxtell.com/

 

[exsnafu]

guess im a little fuzzy on your requirements but if you just want to see if a file contains a string and do something if it does then simply:

grep <string> <file> && <command>

 

[Annihilannic]

Consider also using the grep -q option if you want to do it silently, or if that option is not available on your OS, redirect the output to /dev/null. Another syntax more appropriate for multiple commands would be:

if grep -q <string> <file>
then
    echo "do something"
else
    echo "do something else"
fi

Annihilannic.

 

[khalidaaa]

awk is a very good tool for such cases:

http://www.regatta.cs.msu.su/doc/usr/share/man/info/ru_RU/a_doc_lib/cmds/aixcmds1/awk.htm

http://lowfatlinux.com/linux-awk.html

sed command can be used if you want to do manupilation to the file directly

http://www.regatta.cs.msu.su/doc/usr/share/man/info/ru_RU/a_doc_lib/cmds/aixcmds5/sed.htm#HDRA10793B

Regards,
Khalid

 

[feherke]

Hi

Regarding the second part of your "or", in case this was also part of the question :

if <any member of this list exists>

See if your [tt]grep[/tt] implementation supports the -f option :

[tt] -f FILE, --file=FILE
Obtain patterns from FILE, one per line. The empty file
contains zero patterns, and therefore matches nothing. (-f is
specified by POSIX.)[/tt]

grep -qf <file-with-strings> <file-to-search> && <command>

[gray]# or[/gray]

echo <list-of-strings> | grep -qf - <file-to-search> && <command>

Tested with GNU [tt]grep[/tt].

Feherke.

http://free.rootshell.be/~feherke/