diffutils: patch Input
10.1 Selecting the 'patch' Input Format
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'patch' normally determines which 'diff' format the patch file uses by
examining its contents. For patch files that contain particularly
confusing leading text, you might need to use one of the following
options to force 'patch' to interpret the patch file as a certain format
of diff. The output formats listed here are the only ones that 'patch'
can understand.
'-c'
'--context'
context diff.
'-e'
'--ed'
'ed' script.
'-n'
'--normal'
normal diff.
'-u'
'--unified'
unified diff.