Update cheatsheets

tldr/linux/systemctl-help

@@ -0,0 +1,29 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# systemctl help
+
+> Show the manual pages for one or more units, or for the unit a process belongs to (by PID).
+> More information: <https://www.freedesktop.org/software/systemd/man/systemctl.html#help%20PATTERN%E2%80%A6%7CPID%E2%80%A6>.
+
+- Show the manual page for a specific unit:
+
+`systemctl help {{unit}}`
+
+- Show the manual pages for multiple units:
+
+`systemctl help {{unit1 unit2 ...}}`
+
+- Show the manual page for a user unit:
+
+`systemctl help {{unit}} --user`
+
+- Show the manual page without a pager (all at once):
+
+`systemctl help {{unit}} --no-pager`
+
+- Show the manual page for the unit of a process by PID:
+
+`systemctl help {{pid}}`