Linux+ Bash Scripting and Automation Flashcards

Which Bash test expression correctly checks if a file exists AND is readable?

Answer: [[ -e file && -r file ]]

[[ -e file && -r file ]] uses the modern double-bracket syntax with && to combine both existence and readability tests.

What does the trap command accomplish in a Bash script?

Answer: Registers a handler to execute when a signal or event occurs

trap associates a command or function with a signal (like INT or EXIT) so cleanup code runs on termination.

In Bash arithmetic, which syntax evaluates an integer expression and returns its value?

Answer: $(( expr ))

$(( expr )) is the POSIX-compliant arithmetic expansion syntax for integer math in Bash.

Which getopts usage correctly parses a script option '-f' that requires an argument?

Answer: getopts 'f:' opt

A colon after the option letter in the optstring tells getopts that the option requires an argument, stored in $OPTARG.

What is the output of: echo ${#myvar} when myvar='hello'?

Answer: 5

${#varname} is the Bash parameter expansion that returns the length of the variable's string value.

Which command creates a named pipe (FIFO) in Linux?

Answer: mkfifo

mkfifo creates a named pipe (FIFO special file) that allows inter-process communication via the filesystem.

A script uses 'exec 3< inputfile'. What does file descriptor 3 now represent?

Answer: A read-only file descriptor open on inputfile

exec 3< inputfile opens inputfile for reading on file descriptor 3, allowing the script to read from it independently of stdin.