Update cheatsheets

tldr/linux/systemctl-is-failed

@@ -0,0 +1,26 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# systemctl is-failed
+
+> Check if one or more systemd units have failed.
+> See also: `systemctl is-active`, `systemctl status`.
+> More information: <https://www.freedesktop.org/software/systemd/man/systemctl.html#is-failed%20PATTERN%E2%80%A6>.
+
+- Check if there are any failed units:
+
+`systemctl is-failed`
+
+- Check if a unit or multiple units have failed:
+
+`systemctl is-failed {{unit1 unit2 ...}}`
+
+- Suppress output and return only the exit code:
+
+`systemctl is-failed {{unit}} {{[-q|--quiet]}}`
+
+- Check if a user unit has failed:
+
+`systemctl is-failed {{unit}} --user`