linuxexpert-practice-labs/labs/rhcsa/3-1-conditions

RHCSA 3.1: Conditions and tests

Scripts that test files, the user running them, whether a user exists, and whether a service is running.

Before you start

Write each script where its task says, and make it executable by everyone. The checks run your scripts, as root and as an unprivileged user; the check for task 4 stops chronyd first and starts it again afterwards if your script didn't.

Tasks

1. Write /usr/local/bin/kind that prints file, directory or missing for the path given as its first argument.
2. Write /usr/local/bin/amiroot that prints root and exits 0 when run as root, and prints not root and exits 1 otherwise.
3. Write /usr/local/bin/userexists that takes a user name and prints whether that user exists: NAME exists or NAME does not exist.
4. Write /usr/local/bin/start-chronyd that starts chronyd if it isn't running and does nothing otherwise (it prints nothing then).

Hints

• [ -d ], [ -f ], [ -e ]; if, elif, else, fi.
• id -u is 0 for root, or $EUID; exit 1.
• id NAME >/dev/null 2>&1 or getent passwd NAME.
• systemctl is-active --quiet chronyd || systemctl start chronyd.
• Start each script with #!/bin/bash; chmod 755.