Interview › Scripting (Bash, Groovy)
What is OPTARG, and how does getopts handle options with values? [Intermediate]
Answer
OPTARG holds the value for the current option when getopts processes an option that requires an argument. getopts knows an option requires a value when the option character is followed by a colon in the option string.
Technical explanation
For example, in getopts ':f:t:' both -f and -t require values.
A leading colon in the option string lets the script handle missing values and invalid options explicitly.
OPTIND tracks the next argument index and is used for shifting after option parsing.
Hands-on example
file=""
threshold=80
while getopts ":f:t:" opt; do
case "$opt" in
f) file="$OPTARG" ;;
t) threshold="$OPTARG" ;;
:) echo "missing value for -$OPTARG" >&2; exit 2 ;;
\?) echo "invalid option -$OPTARG" >&2; exit 2 ;;
esac
done
: "${file:?file is required with -f}
Check how well your resume matches the role with our free resume checker— match score, ATS check, and the skills you're missing.
More Scripting (Bash, Groovy) interview questions
- What is the purpose of the shebang line, and what does #!/bin/bash do? [Basic]
- What is the difference between sh and bash? [Basic]
- How do you make a script executable and run it? [Basic]
- What is the difference between running a script with ./script.sh, bash script.sh, and source script.sh? [Basic]
- What does sourcing a script do differently from executing it? [Basic]
- How do you declare a variable in Bash, and why are spaces around = not allowed? [Basic]
- What is the difference between $var and ${var}? [Basic]
- What is the difference between single quotes and double quotes in Bash? [Basic]