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ulimit and process limits: open files, processes, core

cheat sheet · Ubuntu 24.04 · bash 5.2 · systemd 255 https://lab.dimsanych.ru/en/wiki/ulimit/

Cheat sheet

ulimit -a all limits of the shell
ulimit -Sn; ulimit -Hn soft and hard open files limit
ulimit -Sn 4096 raise only the soft one, up to hard
cat /proc/1234/limits limits of a running process
ls /proc/1234/fd | wc -l how many files it holds now
sudo prlimit --pid 1234 --nofile=4096:8192 change on the fly
systemctl show app -p LimitNOFILE -p LimitNOFILESoft