Error in using if condition in Unix shell script

Question

I have written the following shell script:

#!/bin/ksh
main()
{
    echo 'Checking if process is running...'
    if [ [ps -ef|grep "Djava.security.auth.login.config"|grep -v grep|wc -l] != 0 ]; then
            echo "startEventProcessorScript is not running"
            nohup /apps/fasigw/test/bin/startEventProcessor &
    fi

    echo '******************************************************************'
    echo ' Script started successfully '
    echo '******************************************************************'
}
main $*

When I am executing the above script, I get the following error message:

Checking if process is running...
main[3]: test: ] missing
wc: illegal option -- ]
usage: wc [-c|-m] [-lw] [name ...]

I am unable to fix this issue. startEventProcessor is a script that is in path /apps/fasigw/test/bin. Please help

Shawn Chin · Accepted Answer · 2013-01-16 09:54:40Z

3

To get the output of a command within your if statement, you should use command substitution, i.e. use $(...) instead of [..].

if [ $(ps -ef|grep "Djava.security.auth.login.config"|grep -v grep|wc -l) != 0 ]

Note that this can be simplified to:

if [ $(pgrep -cf "Djava.security.auth.login.config") != 0 ]

or :

if ps -ef | grep -q "[D]java.security.auth.login.config"; then

(the brackets in the "[D]java..." is a trick often used to ensure that the grep command does not match its own process).

edited Jan 16, 2013 at 9:54

answered Jan 16, 2013 at 9:44

Shawn Chin

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