The touch command in Linux
touch was designed to update file timestamps, but in everyday use it is the standard way to create an empty file. If the file does not exist, touch creates it; if it does, touch simply updates its modification time and leaves the content untouched — which makes it safe to run on existing files.
How touch works
Every inode stores three timestamps: atime (last read), mtime (last content change) and ctime (last metadata change). touch is a small front-end over the system calls that set them — and when the file is missing, it creates it by opening with the O_CREAT flag, which is why "create an empty file" became its everyday job.
A subtlety worth knowing: you can set atime and mtime freely on your own files, but ctime cannot be set to an arbitrary value by anyone — the kernel updates it itself whenever the inode changes. Forensics and backup tools rely on exactly this property. And on modern systems, atime is often updated lazily (the relatime mount option) to spare disks a write on every read.
Syntax
touch [OPTIONS] FILE...Common options
| Option | What it does |
|---|---|
-c | Do not create the file if it does not exist (only update timestamps). |
-a | Change only the access time. |
-m | Change only the modification time. |
-t | Set a specific timestamp instead of the current time. |
How to use touch: examples
$ touch notes.mdCreate an empty file named notes.md (or update its timestamp if it exists).
$ touch index.html style.css app.jsCreate several files at once.
$ touch file{1..5}.txtBrace expansion creates file1.txt through file5.txt in one command.
Real-world use cases for touch
Marker files in automation
Long-running jobs often signal completion by creating an empty file: touch /tmp/backup.done. Other scripts or monitoring checks then just test for the file's existence — a primitive but bulletproof coordination mechanism used everywhere in ops.
Forcing a rebuild
Build tools like make decide what to rebuild by comparing timestamps. touch src/main.c updates the file's modification time without changing a byte, convincing make that it changed — the classic way to force one file to recompile.
Try touch yourself
This is a live sandbox with a small filesystem (documents/, notes.txt,
backup.sh…). Nothing you do here can break anything — experiment freely.
Try: touch notes.md
Pro tips and common mistakes
- touch existing-file is completely safe: content is never modified, only timestamps.
- Create many numbered files for testing with brace expansion: touch test-{01..20}.log.
- touch -t 202601010000 file sets an arbitrary timestamp — useful for testing time-based logic.
- If touch fails with "No such file or directory", the parent directory is missing: mkdir -p it first.
Frequently asked questions about touch
Does touch overwrite an existing file?
No. If the file exists, touch only updates its access and modification times. The content is never changed.
What is the difference between touch and echo > file?
touch creates an empty file and preserves existing content; echo "" > file creates the file too but truncates (empties) it if it already exists.
Related commands
Create one or many directories, including whole nested paths with -p.
rmDelete files and directories — and understand -r, -f and why there is no trash bin.
catPrint file contents, number lines, and join multiple files together.
echoPrint text and variables, and write or append to files with > and >>.