Before running this
This is a reference for Bash; commands do not run on this page. Use the matching shell on your own computer. Read the example, expected result and notes before trying it. New to terminals? Start with the shell basics.
Syntax
UPPERCASE words are placeholders to replace. Brackets in the syntax line describe optional arguments; do not type those brackets literally.
test EXPRESSIONExample
if test -f note.txt; then printf "%s\n" "file exists"; fiExpected result
Prints file exists when note.txt is a regular file.
Notes and traps
The [ form requires spaces and a closing ]. Bash [[ … ]] has different parsing rules.
Related commands
Related tasks may need different flags and have different semantics. Check the entry before translating a command between shells.
Official reference ↗Updated 13 September 2026. Examples describe the expected behavior; not every platform is available for execution testing.