The Power of Touch

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If you are using Linux or some kind of Unix you properly have noticed the command touch.

touch [-acm] [-r file] [-t [[CC]YY]MMDDhhmm[.SS]] file [...]

Mostly it is used to create empty files, e.g. to create an empty file called new.txt:

touch new.txt

But it can much more. Originally it was build to manipulate the modification and access times of files. E.g. if you want to trick make to recompile a project just touch a file:

touch project.c

Sometimes if you work with NFS drives of servers with asynchronous time stamps, some applications do not recognize updated files and will work with a cached version for some time. Then you can use touch as dirty work around, e.g.:

touch -m 209901018000 cachedfile.txt

Or give a whole folder identical timestamps.

Have a look at the man page for more information.