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Shell Programming and Scripting

Problem with variable assign

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# 1  
Old 07-18-2013
Problem with variable assign
Hi all, i'm new in shell script. i'm trying to do this:

Code:
mypid="ps | grep whileloop.sh | sed -n 1p | tr -s ' ' | cut -f2 -d' '"

i'm trying to assign the pid number to variable mypid, but it doesn't work...how can i do? thanks
Last edited by DukeNuke2; 07-18-2013 at 08:27 AM..
# 2  
Old 07-18-2013
Code:
 
mypid=`ps -ef | grep whileloop.sh | grep -v grep | awk '{print $2}'`

# 3  
Old 07-18-2013
why it is necessary to change my code?
# 4  
Old 07-18-2013
Backticks are deprecated. Use the preferred command substitution $(...):
Code:
mypid=$(ps -ef | awk '/[w]hileloop.sh/ {print $2}' )

# 5  
Old 07-18-2013
Quote:
Originally Posted by Marina2013
why it is necessary to change my code?
Because double quotes " don't do that, backticks ` do. That's what they're for.
# 6  
Old 08-12-2013
Quote:
Originally Posted by Marina2013
i'm trying to assign the pid number to variable mypid
ahem....

The probably shortest and most efficient way to do this is:

Code:
mypid=$$

because "$$" evaluates to the PID of the running process in all POSIX-compatible shells.

I hope this helps.

bakunin
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