Create simple shell scripts

A system administrator needs to create a shell script that checks if the user 'jdoe' exists in the system and, if not, creates the user with a home directory. The script should also verify that the creation was successful. Which of the following script snippets correctly implements this logic?

A developer wrote a shell script that is intended to back up log files by copying all .log files from /var/log/myapp to /backup/logs. The script runs daily via cron but the backup folder is empty. The script contains the following line: `cp /var/log/myapp/*.log /backup/logs/`. What is the most likely reason the backup fails?

An administrator writes a script that uses the 'set -e' option at the top. What is the primary effect of this option?

A system administrator needs to create a shell script that processes a list of hostnames stored in a file, one per line, and runs a command on each host. Which loop construct is most appropriate?

A developer wants to create a script that accepts a directory path as an argument and creates a timestamped backup of that directory. If no argument is provided, it should back up the current directory. How should the script handle the argument?

An administrator writes a script to check disk usage and send an alert if usage exceeds 80%. The script uses 'df -h /' and parses the output. To maintain portability and avoid common pitfalls, which approach is recommended?

A script needs to execute a command that might fail, but the script should continue. The administrator wants to capture the exit status for logging. Which code snippet correctly implements this?

A complex script uses 'trap' to handle signals. The admin writes 'trap '' SIGINT' to ignore Ctrl+C, but later in the script they want to re-enable the default behavior. Which command restores the default behavior for SIGINT?

Which TWO of the following are valid ways to make a shell script executable?

Consider the script in the exhibit. The script is run in a directory containing 'a.txt' and 'b.txt' but also has a subdirectory 'backup' with .txt files. What will be the output?

A developer runs the script shown in the exhibit and always sees 'Success' printed, even when the previous command fails. What is the most likely cause?

You maintain a script that performs a long-running task and must clean up temporary files if the script is interrupted. The script uses: #!/bin/bash tempfile=$(mktemp) trap "rm -f $tempfile" EXIT # long task sleep 100 You notice that if the script receives SIGINT (Ctrl+C), the temporary file is not removed. Investigation shows that the trap on EXIT is not executed on SIGINT. Which modification should be made?