Question

4

pgrep pattern length limit

rated 0 times [ 4] [ 0] / answers: 1 / hits: 4514 / 3 Years ago, fri, june 18, 2021, 3:41:35

pgrep returns nothing if the pattern length is longer than 15 characters.
I can't find anything in the man page about maximum pattern length.

Is this a bug?

for purposes of exposition I created a process called 12345678901234567890

$ pgrep 12345678901234

5367

$ pgrep 123456789012345

5367

$ pgrep 1234567890123456

$

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enincroscope

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2 Years ago

answered 3 Years ago nnaisdio · Accepted Answer

I think it's not a limit on the pattern length in pgrep itself, but a limit on the length of the comm (command) field in the /proc/[pid]/stat files (which is where the information in ps comes from).

According to man proc, the definitions for /proc/[pid]/stat come from /usr/src/linux/fs/proc/array.c so you would need to look there for a definitive answer.