Linux+ 4.2.1: Shell script basics

A script with arguments, a default value and exit codes, and parameter expansion.

Before you start

Work as root, so ~ is /root. The lab only checks that ~/info.sh doesn't exist yet. Write answers to the files in /root/lab-answers/.

Write the executable script ~/info.sh: with set -u, it takes a host as its first argument (default: this machine's hostname), prints Checking HOST (N args, script NAME, PID PID), then pings the host once with a one-second timeout and prints up and exits 0, or prints down and exits 1. Run it with no argument, with 192.0.2.1, and with bash -x and localhost.
Set f=/var/log/nginx/access.log and, with parameter expansion only (no external commands), print on one line: the file name, the directory, the path with .log replaced by .old, the length of the path, and the path in capitals, separated by spaces. Save that line in /root/lab-answers/2.

#!/bin/bash, ${1:-$(hostname)}, $#, $0, $$, if ping -c1 -W1 "$host" >/dev/null 2>&1; then ..., chmod +x, echo "exit $?".
${f##*/}, ${f%/*}, ${f%.log}, ${#f}, ${f^^}.
The chapter's step 2 (export and subshells) isn't graded; try it anyway.