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Old 05-20-2010, 03:29 PM   #1
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Shell Script searches processes running

I'm new to Linux and shell scripting and need to figure out how to write a shell script the searches for processes running on my system. I really don't know where to start. can anyone give me a hand and explain how the script works?
Old 05-20-2010, 03:44 PM   #2
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Does the script need to do something after finding the process it is looking for?

# ps aux

will show you all the processes that are running. Likewise

# top

will show you a bunch of live information about running processes.

If you want to find the process ID without looking through the output of the previous two ideas, pipe the output of ps through grep. Suppose you are looking for the http daemon. Try:

# ps aux | grep httpd

(Note that it will return a line for itself--the grep utility running--so typically if you get one line back, what you're looking for isn't running...)

Do any of those solve your situation?

Good luck.

Old 05-20-2010, 03:46 PM   #3
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There are many tutorials on the net.

A script can be as simply as executing the same commands you type on the screen:

who am i
echo $PATH
For example would tell you information about your current login. Which directory you're sitting in and which directories will be searched when you type a command.

So say you wanted to do something like determine if a specific process (say "fred" was running).

Your script could be as simple as:
ps -ef |grep fred
However since "fred" appears in the process table as an argument to the command "grep" (the one you just piped into) you might want to augment it by telling it NOT to show any line containing the word "grep":

ps -ef |grep fred |grep -v grep
Check out one of the tutorials as they'll walk you through doing scripts - just remember at their basic form they can simply be a set of commands in a file that you might have otherwise typed at command line. They can get much more complex than that but there is no reason not to start doing basic things and add or modify as you learn.
Old 05-20-2010, 07:31 PM   #4
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