Linux – How to apply a patch correctly

It's a patch that undoes the earlier patch. It can be made with patch -R -pX bad.patch (where X is the number of directory levels to strip from the patch and bad.patch is the patch we want to undo) followed by a git commit

A "reversed patch" is when someone accidentally makes a patch with diff -u foo.c foo.c.orig (where foo.c is the newer file) instead of the correct diff -u foo.c.orig foo.c

The "reversed or previous applied patch" error indicates the patch has already been applied. I can not be more specific without knowing the contents of your kernelsuspend.patch file.

If you have the .git directory for the kernel source, you can look at the log for a single file with the git log command followed by the file name. e.g. git log fs/eventpoll.c or even git log -p fs/eventpoll.c.

You need to patch the right file.

The way you call it, it will try to patch the new file and thus correctly assumes a reversed patch.

Try to copy an old version of the file to your current directory and the patch will apply.

Regarding your -p0 test: do you have permission to modify /usr/bin/gradle? Do you have permission to create files in /usr/bin?

Also note that there are deviating rules for getting the filename to patch.

The rules used by gpatch are different from both the original patch and the POSIX patch standard.

Note that the "not a regular file" message is specific to gpatch. Please list the file /usr/bin/gradle. The message is only printed when the file is not a regular file, so something looks strange.

So the solution is:

patch only patches plain files but the file you like to patch is a symbolic link.

If you have a copy of the plain (old version) file in your current directory, patch will do what you expect.

BTW: the usual rule for getting the file name to patch is to look for the shortest name as the usual naming convention is to use:

file.orig

and

file