Clobber (computing)

In software engineering, clobbering a file or computer memory is overwriting its contents.

Jargon File defines the term as follows: "To overwrite, usually unintentionally: “I walked off the end of the array and clobbered the stack.” Compare mung, scribble, trash, and smash the stack."^[1]

Often this happens unintentionally, e.g., using the '>' redirection operator. To prevent unintentional clobbering, various means are used. For example, the setting shell parameter "set -o noclobber" (bash, ksh) or "set noclobber" (csh, tcsh) will prevent '>' from clobbering making it to issue an error message instead:^[2]

>set -o noclobber
>echo hello > bb
>echo hello > bb
bb: File exists.

In makefiles, a common target clobber means complete cleanup of all unnecessary files and directories produced by previous invocations of the make command.^[3] It is a more severe target than clean and is commonly used to uninstall software. Some make-related commands invoke "make clobber" during their execution. They check the CLOBBER environment variable. If it is set to OFF then clobbering is not done.^[4]

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