Hi

Can anybody please tell me about patch in linux?

For what purpose patch is created and used?

Regards,

karthik

If you run "man patch" on any Linux or Unix based system, or search the web for "man patch", "patch manual" etc, you will get detailed info about what patch is and what it does.

man patch:

patch takes a patch file patchfile containing a difference listing pro-
duced by the diff program and applies those differences to one or more
original files, producing patched versions.

In other words it's used to apply precreated (usuall with diff command) patches (=lists of changes to be made) to files.

Thanks alien!

can we say patch is like program to fill the defectives of
previous version of one program?

regards,

karthik

Good link taken directly from the kernel source:

http://developer.osdl.org/dev/robust...ng-patches.txt


A patch is a text document to change something from one version to another. As you said, it can correct bug but can also add some special functionnality.

In the "old days," patches were used a lot more because they were smaller than the source-files that they patched. Nowadays they are most useful for documenting the differences between the "old" and "new" version of a particular text-file. Any difference, no matter how slight, will be detected.

patch can take a patch-file and source-file as input and produce a modified source-file as output. The process is based on the diff (file-difference) command and it's quite "smart."

The contents of a patch-file are contextual, not based on line-numbers but on content. The CVS version-control system is also based on this technology.