RHCSA Shell Scripting and Automation Flashcards

Which command redirects both stdout and stderr to a file called `output.log`?

Answer: command > output.log 2>&1

Redirecting stdout to a file with `>` and then redirecting stderr (`2>`) to stdout (`&1`) sends both streams to the same file.

In Bash, what does the `test -f /etc/passwd` command check?

Answer: Whether /etc/passwd exists and is a regular file

The `-f` flag in `test` returns true if the given path exists and is a regular (non-directory) file.

What does `#!/bin/bash -x` at the top of a script do?

Answer: Enables debug mode, printing each command before execution

The `-x` flag enables shell trace mode, printing each command and its arguments to stderr before execution.

Which construct in Bash allows you to define a reusable block of commands?

Answer: function

Bash supports defining reusable blocks using the `function` keyword or the `name() { }` syntax.

What is the purpose of `set -e` at the beginning of a Bash script?

Answer: Exit the script immediately if any command returns a non-zero status

`set -e` causes the script to exit immediately when any command exits with a non-zero (failure) status.

Which Bash arithmetic syntax correctly computes the sum of variables A and B?

Answer: $((A + B))

The `$(( ))` arithmetic expansion performs integer arithmetic directly within Bash without calling external commands.