add directory-examining recursive compare derp(1)

1 files changed, 132 insertions, 0 deletions

diff --git a/sys/man/1/derp b/sys/man/1/derp
new file mode 100644
index 000000000..91467238d
--- /dev/null
+++ b/sys/man/1/derp
@@ -0,0 +1,132 @@
+.TH DERP 1
+.SH NAME
+derp \- directory-examining recursive compare
+.SH SYNOPSIS
+.B derp
+[
+.B -qcutDL
+] [
+.B -p
+.I perms
+] 
+.I myfile
+.I oldfile
+.I yourfile
+.SH DESCRIPTION
+.I Derp
+recursively compares the two directories
+.I myfile
+and
+.I yourfile
+using a third common backup directory
+.I oldfile
+as reference. The changes found are printed
+to standard output, one per line, with the file
+status describing either side followed by tabulator
+and the relative file path.
+.LP
+The possible status codes:
+.TP
+.B an
+File added in
+.I myfile
+.TP
+.B na
+File added in
+.I yourfile
+.TP
+.B aa!
+Both sides added different files with the
+same name
+.TP
+.B mn
+File was modified in
+.I myfile
+.TP
+.B nm
+File was modified in
+.I yourfile
+.TP
+.B mm!
+File was changed differently in
+.I myfile
+and
+.I yourfile
+.TP
+.B dn
+File was deleted in
+.I myfile
+.TP
+.B nd
+File was deleted in
+.I yourfile
+.TP
+.B md!
+File was modified in
+.I myfile
+but deleted in
+.I yourfile
+.TP
+.B dm!
+File was modified in
+.I yourfile
+but deleted in
+.I myfile
+.LP
+Errors are printed to standard error unless
+.B -q
+option is specified. The program is terminated
+when errors are encountered unless the
+.B -c
+option is given. This can be usefull if files
+are not accessible due to file permission or
+media corruption.
+.PP
+The
+.B -u
+option will consider changes of file owner and group.
+When omited, file ownership is ignored.
+.PP
+The
+.B -p
+option sets the octal mask
+.I perms
+of bits to check in the file permissions. The default
+ignores file permissions.
+.PP
+When modification times are comparable then the
+.B -t
+option can be used to quickly find changes. If specified,
+files are considered unchanged if the name, file size and
+the modification time matches. This is usefull when
+comparing /n/dump archives on the same fileserver.
+.PP
+Files are considered the same if they are from the
+same mount and ther
+.B qid
+(see
+.IR stat (5))
+matches. For directories, the access time is also
+compared. If the access time was disabled on the
+fileserver, then all directories need to be compared
+using the
+.B -D
+option.
+.PP
+Some filesystems like
+.IR hgfs (4)
+do not always return exact file size in stat, so
+the length check can be disabled with the
+.B -L
+option.
+.SH SOURCE
+.B /sys/src/cmd/derp.c
+.SH "SEE ALSO"
+.IR cmp (1),
+.IR diff (1),
+.IR history (1),
+.IR fs (4),
+.IR hgfs (4)
+.SH DIAGNOSTICS
+The exit status is set to 'errors' when
+errors where encountered.