Interview › Scripting (Bash, Groovy)
Why do the brackets in [ ... ] require spaces? [Basic]
Answer
The brackets in [ ... ] require spaces because [ is actually a command name and ] is its final argument. Without spaces, the shell sees a different token, not the test command syntax.
Technical explanation
[ -f file ] is equivalent to running the test command with arguments.
[ -ffile] or [-f file ] is parsed incorrectly because command tokens are separated by whitespace.
[[ ... ]] is shell syntax rather than an external-style command, but spacing is still required around the keywords and operators.
Hands-on example
# Correct:
if [ -f "config.yaml" ]; then
echo "exists"
fi
# Incorrect:
# if [-f "config.yaml"]; then ...
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