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Mac Magazin/MacEasy 34
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Mac Magazin and MacEasy Magazine CD - Issue 34.iso
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1994-09-04
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DIFF(1) USER COMMANDS DIFF(1)
NAME
diff - display line-by-line differences between pairs of
text files
SYNOPSIS
diff [ -bitw ] [ -c [ # ] | -e | -f | -n | -h ] filename1
filename2
diff [ -bitw ] [ -Dstring ] filename1 filename2
diff [ -bitw ] [ -c [ # ] | -e | -f | -n | -h ] [ -l ] [ -r
] [ -s ] [ -Sname ] directory1 directory2
DESCRIPTION
diff is a differential file comparator. When run on regular
files, and when comparing text files that differ during
directory comparison (see the notes below on comparing
directories), diff tells what lines must be changed in the
files to bring them into agreement. Except in rare cir-
cumstances, diff finds a smallest sufficient set of differ-
ences. If neither filename1 nor filename2 is a directory,
either may be given as `-', in which case the standard input
is used. If filename1 is a directory, a file in that direc-
tory whose filename is the same as the filename of filename2
is used (and vice versa).
There are several options for output format; the default
output format contains lines of these forms:
n1 a n3,n4
n1,n2 d n3
n1,n2 c n3,n4
These lines resemble ed(1) commands to convert filename1
into filename2. The numbers after the letters pertain to
filename2. In fact, by exchanging a for d and reading back-
ward one may ascertain equally how to convert filename2 into
filename1. As in ed(1), identical pairs, where n1 = n2 or
n3 = n4, are abbreviated as a single number.
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 `>'.
If both arguments are directories, diff sorts the contents
of the directories by name, and then runs the regular file
diff program as described above on text files which are dif-
ferent. Binary files which differ, common subdirectories,
and files which appear in only one directory are listed.
OPTIONS
-b Ignore trailing blanks (SPACE and TAB characters) and
treat all other strings of blanks as equivalent.
Sun Release 4.1 Last change: 2 October 1989 1
DIFF(1) USER COMMANDS DIFF(1)
-i Ignore the case of letters; for example, `A' will com-
pare equal to `a'.
-t Expand TAB characters in output lines. Normal or -c
output adds character(s) to the front of each line
which may alter the indentation of the original source
lines and make the output listing difficult to inter-
pret. This option will preserve the original source's
indentation.
-w Ignore all blanks (SPACE and TAB characters); for exam-
ple, `if ( a == b )' will compare equal to `if(a==b)'.
The following four options are mutually exclusive:
-c[#]
Produce a listing of differences with lines of context.
The default is to present 3 lines of context and may be
changed, (to 10, for example), by -c10. With -c the
output format is modified slightly: output begins with
identification of the files involved and their creation
dates, then each change is separated by a line with a
dozen *s. The lines removed from filename1 are marked
with `- '; those added to filename2 are marked `+ '.
Lines which are changed from one file to the other are
marked in both files with `! '.
Changes which lie within <context> lines of each other
are grouped together on output. This is a change from
the previous `diff -c' but the resulting output is usu-
ally much easier to interpret.
-e Produce a script of a, c, and d commands for the editor
ed, which will recreate filename2 from filename1.
In connection with -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
ed scripts ($2,$3,...) made by diff need be on hand. A
`latest version' appears on the standard output.
(shift; cat $*; echo '1,$p') | ed - $1
Extra commands are added to the output when comparing
directories with -e, so that the result is a sh script
for converting text files which are common to the two
directories from their state in directory1 to their
state in directory2.
-f Produce a script similar to that of -e, not useful with
ed, which is in the opposite order.
-n Produce a script similar to that of -e, but in the
Sun Release 4.1 Last change: 2 October 1989 2
DIFF(1) USER COMMANDS DIFF(1)
opposite order and with a count of changed lines on
each insert or delete command.
-h Do 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 for the second form of diff are as follows:
-Dstring
Create a merged version of filename1 and filename2 on
the standard output, with C preprocessor controls
included so that a compilation of the result without
defining string is equivalent to compiling filename1,
while defining string will yield filename2.
Options when comparing directories are:
-l Long output format; each text file diff is piped
through pr(1V) to paginate it, other differences are
remembered and summarized after all text file differ-
ences are reported.
-r Apply diff recursively to common subdirectories encoun-
tered.
-s Report files which are the same, which are otherwise
not mentioned.
-Sname
Start a directory diff in the middle, beginning with
file name.
ENVIRONMENT
The environment variables LC_CTYPE, LANG, and LC_default
control the character classification throughout diff. On
entry to diff, these environment variables are checked in
the following order: LC_CTYPE, LANG, and LC_default. When a
valid value is found, remaining environment variables for
character classification are ignored. For example, a new
setting for LANG does not override the current valid charac-
ter classification rules of LC_CTYPE. When none of the
values is valid, the shell character classification defaults
to the POSIX.1 "C" locale.
FILES
/tmp/d?????
/usr/lib/diffh for -h
SEE ALSO
cc(1V), cmp(1), comm(1), cpp(1), diff3(1V), ed(1), pr(1V),
locale(5), iso_8859_1(7)
Sun Release 4.1 Last change: 2 October 1989 3
DIFF(1) USER COMMANDS DIFF(1)
DIAGNOSTICS
Exit status is 0 for no differences, 1 for some differences,
2 for trouble.
Missing newline at end of fileX
Indicates that the last line of file X did not have a
NEWLINE. If the lines are different, they will be
flagged and output, although the output will seem to
indicate they are the same.
BUGS
Editing scripts produced under the -e or -f option are naive
about creating lines consisting of a single `.'.
When comparing directories with the -b, -w, or -i options
specified, diff first compares the files (as in cmp(1), and
then runs the regular diff algorithm if they are not equal.
This may cause a small amount of spurious output if the
files then turn out to be identical because the only differ-
ences are insignificant blank string or case differences.
The -D option ignores existing preprocessor controls in the
source files, and can generate #ifdefs's with overlapping
scope. The output should be checked by hand, or run through
`cc -E' (see cc(1V)) and then diffed with the original
source files. Discrepancies revealed should be corrected
before compilation.
Sun Release 4.1 Last change: 2 October 1989 4
Enter Unix command line:
Usage: diff [-#] [-abBcdefhHilnNprstTuvw] [-C lines] [-F regexp] [-I regexp]
[-L label [-L label]] [-S file] [-D symbol] [+ignore-blank-lines]
[+context[=lines]] [+unified[=lines]] [+ifdef=symbol]
[+show-function-line=regexp]
[+speed-large-files] [+ignore-matching-lines=regexp] [+new-file]
[+initial-tab] [+starting-file=file] [+text] [+all-text] [+ascii]
[+minimal] [+ignore-space-change] [+ed] [+reversed-ed] [+ignore-case]
[+print] [+rcs] [+show-c-function] [+binary] [+brief] [+recursive]
[+report-identical-files] [+expand-tabs] [+ignore-all-space]
[+file-label=label [+file-label=label]] [+version] path1 path2