linuxexpert-practice-labs/labs/lpic-1/104-7-fhs-and-finding-files

LPIC-1 104.7: The FHS and finding files

Where a service's files live, the locate database and what it leaves out, and the different ways to look up a command.

Before you start

The lab installs plocate if it's missing, creates /srv/archive/ with a few old files in it, and builds the locate database. It saves /etc/updatedb.conf; reset puts it back. Work as root (sudo -i), and write answers to the files in /root/lab-answers/.

Tasks

1. Take sshd. Find its program, configuration, logs, runtime files and man pages, and say why each lives where it does. Write one path (or command) per line to /root/lab-answers/1: the program, the main configuration file, where its log messages go, a runtime file under /run, and its man page.
2. Create a file, locate it, run updatedb as root, and locate it again. Delete it and compare locate with locate -e. Write which of the two still lists the deleted file to /root/lab-answers/2.
3. Add /srv/archive to PRUNEPATHS in /etc/updatedb.conf, run updatedb, and show that its files are no longer found.
4. Compare which -a, type -a and whereis for ls, passwd and cd. Write what type -a cd prints to /root/lab-answers/4.
5. Time locate passwd against find / -name passwd 2>/dev/null with time. Check it yourself: locate answers in milliseconds.

Hints

• command -v sshd, systemctl cat sshd (ssh on Ubuntu), ls /etc/ssh, journalctl -u, ls /run, man -w sshd.
• locate searches a database that only updatedb refreshes; -e checks that each file still exists.
• PRUNEPATHS is a space-separated list in double quotes.
• type knows about builtins and aliases; which and whereis only about files.