to remove output files that are empty after the patches have been applied..TP 5.B \-fforces.I patchto assume that the user knows exactly what he or she is doing, and to notask any questions.  It assumes the following: skip patches for which afile to patch can't be found; patch files even though they have thewrong version for the ``Prereq:'' line in the patch; and assume thatpatches are not reversed even if they look like they are.This option does not suppress commentary; use.B \-sfor that..TP 5.B \-tsimilar to.BR \-f ,in that it suppresses questions, but makes some different assumptions:skip patches for which a file to patch can't be found (the same as \fB\-f\fP);skip patches for which the file has the wrong version for the ``Prereq:'' linein the patch; and assume that patches are reversed if they look likethey are..TP 5.B \-F<number>sets the maximum fuzz factor.This switch only applies to context diffs, and causes.I patchto ignore up to that many lines in looking for places to install a hunk.Note that a larger fuzz factor increases the odds of a faulty patch.The default fuzz factor is 2, and it may not be set to more thanthe number of lines of context in the context diff, ordinarily 3..TP 5.B \-lcauses the pattern matching to be done loosely, in case the tabs andspaces have been munged in your input file.Any sequence of whitespace in the pattern line will match any sequencein the input file.Normal characters must still match exactly.Each line of the context must still match a line in the input file..TP 5.B \-nforces.I patchto interpret the patch file as a normal diff..TP 5.B \-Ncauses.I patchto ignore patches that it thinks are reversed or already applied.See also.B \-R ..TP 5.B \-ocauses the next argument to be interpreted as the output file name..TP 5.B \-p<number>sets the pathname strip count,which controls how pathnames found in the patch file are treated, in casethe you keep your files in a different directory than the person who sentout the patch.The strip count specifies how many slashes are to be stripped fromthe front of the pathname.(Any intervening directory names also go away.)For example, supposing the filename in the patch file was.sp	/u/howard/src/blurfl/blurfl.c.spsetting.B \-por.B \-p0gives the entire pathname unmodified,.B \-p1gives.sp	u/howard/src/blurfl/blurfl.c.spwithout the leading slash,.B \-p4gives.sp	blurfl/blurfl.c.spand not specifying.B \-pat all just gives you "blurfl.c", unless all of the directories in theleading path (u/howard/src/blurfl) exist and that path is relative,in which case you get the entire pathname unmodified.Whatever you end up with is looked for either in the current directory,or the directory specified by the.B \-dswitch..TP 5.B \-rcauses the next argument to be interpreted as the reject file name..TP 5.B \-Rtells.I patchthat this patch was created with the old and new files swapped.(Yes, I'm afraid that does happen occasionally, human nature being what itis.).I Patchwill attempt to swap each hunk around before applying it.Rejects will come out in the swapped format.The.B \-Rswitch will not work with ed diff scripts because there is too littleinformation to reconstruct the reverse operation..SpIf the first hunk of a patch fails,.I patchwill reverse the hunk to see if it can be applied that way.If it can, you will be asked if you want to have the.B \-Rswitch set.If it can't, the patch will continue to be applied normally.(Note: this method cannot detect a reversed patch if it is a normal diffand if the first command is an append (i.e. it should have been a delete)since appends always succeed, due to the fact that a null context will matchanywhere.Luckily, most patches add or change lines rather than delete them, so mostreversed normal diffs will begin with a delete, which will fail, triggeringthe heuristic.).TP 5.B \-smakes.I patchdo its work silently, unless an error occurs..TP 5.B \-Scauses.I patchto ignore this patch from the patch file, but continue on lookingfor the next patch in the file.Thus.sp	patch -S + -S + <patchfile.spwill ignore the first and second of three patches..TP 5.B \-uforces.I patchto interpret the patch file as a unified context diff (a unidiff)..TP 5.B \-vcauses.I patchto print out its revision header and patch level..TP 5.B \-Vcauses the next argument to be interpreted as a method for creatingbackup file names.  The type of backups made can also be given in the.B VERSION_CONTROLenvironment variable, which is overridden by this option.The.B -Boption overrides this option, causing the prefix to always be used formaking backup file names.The value of the.B VERSION_CONTROLenvironment variable and the argument to the.B -Voption are like the GNUEmacs `version-control' variable; they also recognize synonyms thatare more descriptive.  The valid values are (unique abbreviations areaccepted):.RS.TP`t' or `numbered'Always make numbered backups..TP`nil' or `existing'Make numbered backups of files that alreadyhave them, simple backups of the others.This is the default..TP`never' or `simple'Always make simple backups..RE.TP 5.B \-x<number>sets internal debugging flags, and is of interest only to.I patchpatchers..SH AUTHORLarry Wall <lwall@netlabs.com>.brwith many other contributors..SH ENVIRONMENT.TP.B TMPDIRDirectory to put temporary files in; default is /tmp..TP.B SIMPLE_BACKUP_SUFFIXExtension to use for backup file names instead of \*(L".orig\*(R" or\*(L"~\*(R"..TP.B VERSION_CONTROLSelects when numbered backup files are made..SH FILES$TMPDIR/patch*.SH SEE ALSOdiff(1).SH NOTES FOR PATCH SENDERSThere are several things you should bear in mind if you are going tobe sending out patches.First, you can save people a lot of grief by keeping a patchlevel.h filewhich is patched to increment the patch level as the first diff in thepatch file you send out.If you put a Prereq: line in with the patch, it won't let them applypatches out of order without some warning.Second, make sure you've specified the filenames right, either in acontext diff header, or with an Index: line.If you are patching something in a subdirectory, be sure to tell the patchuser to specify a .B \-pswitch as needed.Third, you can create a file by sending out a diff that compares anull file to the file you want to create.This will only work if the file you want to create doesn't exist already inthe target directory.Fourth, take care not to send out reversed patches, since it makes people wonderwhether they already applied the patch.Fifth, while you may be able to get away with putting 582 diff listings intoone file, it is probably wiser to group related patches into separate files incase something goes haywire..SH DIAGNOSTICSToo many to list here, but generally indicative that.I patchcouldn't parse your patch file..PPThe message \*(L"Hmm...\*(R" indicates that there is unprocessed text inthe patch file and that.I patchis attempting to intuit whether there is a patch in that text and, if so,what kind of patch it is..PP.I Patchwill exit with a non-zero status if any reject files were created.When applying a set of patches in a loop it behooves you to check thisexit status so you don't apply a later patch to a partially patched file..SH CAVEATS.I Patchcannot tell if the line numbers are off in an ed script, and can only detectbad line numbers in a normal diff when it finds a \*(L"change\*(R" ora \*(L"delete\*(R" command.A context diff using fuzz factor 3 may have the same problem.Until a suitable interactive interface is added, you should probably doa context diff in these cases to see if the changes made sense.Of course, compiling without errors is a pretty good indication that the patchworked, but not always..PP.I Patchusually produces the correct results, even when it has to do a lot ofguessing.However, the results are guaranteed to be correct only when the patch isapplied to exactly the same version of the file that the patch wasgenerated from..SH BUGSCould be smarter about partial matches, excessively \&deviant offsets andswapped code, but that would take an extra pass..PPIf code has been duplicated (for instance with #ifdef OLDCODE ... #else ...#endif),.I patchis incapable of patching both versions, and, if it works at all, will likelypatch the wrong one, and tell you that it succeeded to boot..PPIf you apply a patch you've already applied,.I patchwill think it is a reversed patch, and offer to un-apply the patch.This could be construed as a feature..rn }` ''