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touch

summary

    This subchapter looks at touch, a Unix (and Linux) command.

    Use touch to change the date stamp on a file.

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touch

    This subchapter looks at touch, a Unix (and Linux) command.

    Use touch to change the date stamp on a file.

    The most common use of touch is to force make to recompile a particular file (or group of files).

how to use

    The simple form of touch changes a named file’s timestamp to the current date and time:

$ touch filename

multiple files

    Use touch to change all of the files in a directory:

$ touch *

specific time

    You can use touch to set a specific time by using the -t option. The following command sets a file to the Solstice at the end of the Mayan calendar (11:12 a.m. December 21, 2012):

$ touch -t201212211112.00 filename

    The following command sets a file to the noon on January 1, 2012:

$ touch -t201201011200.00 filename

    The format is YYYYMMDDhhmm.ss, YYYY = four digit year, MM - two digit month, DD = two digit day, hh = two digit hour (24 hour clock), mm = two digit month, and ss = two digit second.

create an empty file

    You can use touch to create an empty file. Simply issue the touch command with the desired file name.

$ touch filename

    This will create an empty file with the designated file name.

    Why would you want to do this? One common reason is to create an expected file. Some scripts will check for the existence of particular files and choke if they can’t find them. If the script does not need particular data alreazdy stored in the file (for example, it will be appending data intot he file or it is simply checking for the existence of the file), then touch is your fast and easy method for creating the expected file (as an empty file).

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