[unix-history] / usr / man / man1 / diff.1

.TH DIFF 1 
.SH NAME
diff \- differential file comparator
.SH SYNOPSIS
.B diff
[
.B \-efbh
] file1 file2
.SH DESCRIPTION
.I Diff
tells what lines must be changed in two files to bring them
into agreement.
If
.I file1
.RI ( file2 )
is `\-', the standard input is used.
If
.I file1
.RI ( file2 )
is a directory, then a file in that directory
whose file-name is the same as the file-name of 
.I file2
.RI ( file1 )
is used.
The normal output contains lines of these forms:
.IP "" 5
.I n1
a
.I n3,n4
.br
.I n1,n2
d
.I n3
.br
.I n1,n2
c
.I n3,n4
.PP
These lines resemble
.I ed
commands to convert
.I file1
into
.IR file2 .
The numbers after the letters pertain to
.IR file2 .
In fact, by exchanging `a' for `d' and reading backward
one may ascertain equally how to convert 
.I file2
into
.IR file1 .
As in 
.I ed,
identical pairs where
.I n1
=
.I n2
or
.I n3
=
.I n4
are abbreviated as a single number.
.PP
Following each of these lines come all the lines that are
affected in the first file flagged by `<', 
then all the lines that are affected in the second file
flagged by `>'.
.PP
The
.B \-b
option causes
trailing blanks (spaces and tabs) to be ignored
and other strings of blanks to compare equal.
.PP
The
.B \-e
option produces a script of
.I "a, c"
and 
.I d
commands for the editor
.I ed,
which will recreate
.I file2
from
.IR file1 .
The
.B \-f
option produces a similar script,
not useful with
.I ed,
in the opposite order.
In connection with
.BR \-e ,
the following shell program may help maintain
multiple versions of a file.
Only an ancestral file ($1) and a chain of 
version-to-version
.I ed
scripts ($2,$3,...) made by
.I diff
need be on hand.
A `latest version' appears on
the standard output.
.IP "" 5
(shift; cat $*; echo \'1,$p\') \(bv ed \- $1
.PP
Except in rare circumstances,
.I diff
finds a smallest sufficient set of file
differences.
.PP
Option
.B \-h
does a fast, half-hearted job.
It works only when changed stretches are short
and well separated,
but does work on files of unlimited length.
Options 
.B \-e
and
.B \-f
are unavailable with
.BR \-h .
.SH FILES
/tmp/d?????
.br
/usr/lib/diffh for 
.B \-h
.SH "SEE ALSO"
cmp(1), comm(1), ed(1)
.SH DIAGNOSTICS
Exit status is 0 for no differences, 1 for some, 2 for trouble.
.SH BUGS
Editing scripts produced under the
.BR \-e " or"
.BR \-f " option are naive about"
creating lines consisting of a single `\fB.\fR'.
Commit	Line	Data
e6817382 BJ	1	.TH DIFF 1
	2	.SH NAME
	3	diff \- differential file comparator
	4	.SH SYNOPSIS
	5	.B diff
	6	[
	7	.B \-efbh
	8	] file1 file2
	9	.SH DESCRIPTION
	10	.I Diff
	11	tells what lines must be changed in two files to bring them
	12	into agreement.
	13	If
	14	.I file1
	15	.RI ( file2 )
	16	is `\-', the standard input is used.
	17	If
	18	.I file1
	19	.RI ( file2 )
	20	is a directory, then a file in that directory
	21	whose file-name is the same as the file-name of
	22	.I file2
	23	.RI ( file1 )
	24	is used.
	25	The normal output contains lines of these forms:
	26	.IP "" 5
	27	.I n1
	28	a
	29	.I n3,n4
	30	.br
	31	.I n1,n2
	32	d
	33	.I n3
	34	.br
	35	.I n1,n2
	36	c
	37	.I n3,n4
	38	.PP
	39	These lines resemble
	40	.I ed
	41	commands to convert
	42	.I file1
	43	into
	44	.IR file2 .
	45	The numbers after the letters pertain to
	46	.IR file2 .
	47	In fact, by exchanging `a' for `d' and reading backward
	48	one may ascertain equally how to convert
	49	.I file2
	50	into
	51	.IR file1 .
	52	As in
	53	.I ed,
	54	identical pairs where
	55	.I n1
	56	=
	57	.I n2
	58	or
	59	.I n3
	60	=
	61	.I n4
	62	are abbreviated as a single number.
	63	.PP
	64	Following each of these lines come all the lines that are
65	affected in the first file flagged by `<',
66	then all the lines that are affected in the second file
67	flagged by `>'.
68	.PP
69	The
70	.B \-b
71	option causes
72	trailing blanks (spaces and tabs) to be ignored
73	and other strings of blanks to compare equal.
74	.PP
75	The
76	.B \-e
77	option produces a script of
78	.I "a, c"
79	and
80	.I d
81	commands for the editor
82	.I ed,
83	which will recreate
84	.I file2
85	from
86	.IR file1 .
87	The
88	.B \-f
89	option produces a similar script,
90	not useful with
91	.I ed,
92	in the opposite order.
93	In connection with
94	.BR \-e ,
95	the following shell program may help maintain
96	multiple versions of a file.
97	Only an ancestral file ($1) and a chain of
98	version-to-version
99	.I ed
100	scripts ($2,$3,...) made by
101	.I diff
102	need be on hand.
103	A `latest version' appears on
104	the standard output.
105	.IP "" 5
106	(shift; cat $*; echo \'1,$p\') \(bv ed \- $1
107	.PP
108	Except in rare circumstances,
109	.I diff
110	finds a smallest sufficient set of file
111	differences.
112	.PP
113	Option
114	.B \-h
115	does a fast, half-hearted job.
116	It works only when changed stretches are short
117	and well separated,
118	but does work on files of unlimited length.
119	Options
120	.B \-e
121	and
122	.B \-f
123	are unavailable with
124	.BR \-h .
125	.SH FILES
126	/tmp/d?????
127	.br
128	/usr/lib/diffh for
129	.B \-h
130	.SH "SEE ALSO"
131	cmp(1), comm(1), ed(1)
132	.SH DIAGNOSTICS
133	Exit status is 0 for no differences, 1 for some, 2 for trouble.
134	.SH BUGS
135	Editing scripts produced under the
136	.BR \-e " or"
137	.BR \-f " option are naive about"
138	creating lines consisting of a single `\fB.\fR'.