All of the problems witnessed above are the result of the shell forking to create new processes to run a pipeline: ps, grep, wc, another shell for the command substition (in the case of the original post). All of these processes initially begin as a new shell with the same name, $0, as the parent shell.
If ps scans the process list before any of these shells have had a chance to exec and become the utility it will become, the result is multiple instances of $0.
The solution is trivial and widely available: pgrep
Quote:
Originally Posted by sathyaonnuix
I found out the problem Since we give wc -l, this gets a new line. And hence that has got counted in it.
I changed that to
Now it works cool.
Your analysis is incorrect. You're just getting lucky with timing. In your original wc version, you were unlucky with timing. Nothing has been fixed.
The reason pgrep works reliably is because it's only one command and it doesn't run until after the shell that was forked to create it has exec'd.
Unless the system lacks pgrep and pkill, there's no need to resort to the ps ... | grep/awk ... silliness.
Hi folks,
If a declare a direct hash , then the hash element works fine.
my %test = ("test",1);
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print "\n";
Here in the above, the name of the hash is predeclared...
Suppose now I need to create the hash elements dynamically in the for loop.
$test="hash";
my... (1 Reply)
hi
i am new to shell scripting.
i was going thru the part option and arguments. on this section i fail to understand the use of exit 0 in below example .
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USAGE="Usage: $0 "
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-t) TARGS="-tvf $2" ;;
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exit 0
;;
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Could anybody explain me the following situation.
If I'm running similar script:
Var="anna.kurnikova"
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:confused:
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