diff - compare two files


     diff [-bitw] [-c | -e | -f | -h | -n | -u]  file1 file2

     diff [-bitw] [-C number | -U number]  file1 file2

     diff [-bitw] [-D string] file1 file2

     diff [-bitw] [-c | -e | -f | -h | -n | -u]  [-l]  [-r]  [-s]
     [-S name] directory1 directory2


     The diff utility will compare  the  contents  of  file1  and
     file2  and write to standard output a list of changes neces-
     sary to convert  file1  into  file2.  This  list  should  be
     minimal. Except in rare circumstances, diff finds a smallest
     sufficient set of file differences. No output will  be  pro-
     duced if the files are identical.

     The normal output contains lines of these forms:

     n1 a n3,n4
     n1,n2 d n3
     n1,n2 c n3,n4

     where n1  and  n2  represent  lines  file1  and  n3  and  n4
     represent lines in file2 These lines resemble ed(1) commands
     to convert file1 to file2. By exchanging a for d and reading
     backward, file2 can be converted to file1. As in ed, identi-
     cal pairs, where n1=n2 or n3=n4, are abbreviated as a single

     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 `>'.


     The following options are supported:

     -b    Ignores trailing blanks (spaces and tabs)  and  treats
           other strings of blanks as equivalent.

     -i    Ignores the case of letters.  For  example,  `A'  will
           compare equal to `a'.

     -t    Expands <TAB> characters in output lines. Normal or -c
           output  adds  character(s)  to  the front of each line
           that may adversely affect the indentation of the  ori-
           ginal source lines and make the output lines difficult
           to interpret. This option will preserve  the  original
           source's indentation.

     -w    Ignores all blanks (<SPACE> and <TAB> characters)  and
           treats  all other strings of blanks as equivalent. For
           example,  `if ( a == b )'  will   compare   equal   to

     The following options are mutually exclusive:

     -c    Produces a listing of differences with three lines  of
           context.  With  this option, output format is modified
           slightly. That is, 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 file1 are marked with '-'. The
           lines added to file2 are marked '+'.  Lines  that  are
           changed  from one file to the other are marked in both
           files with '!'.

     -C number
           Produces a listing of differences  identical  to  that
           produced by -c with number lines of context.

     -D string
           Creates a merged version of file1  and  file2  with  C
           preprocessor  controls  included so that a compilation
           of the result without defining string is equivalent to
           compiling  file1,  while  defining  string  will yield

     -e    Produces a script of only a, c, and d commands for the
           editor  ed,  which  will recreate file2 from file1. In
           connection with the -e  option,  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

           (shift; cat $*; echo '1,$p') | ed - $1

     -f    Produces a similar script, not useful with ed, in  the
           opposite order.

     -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  -c,
           -C,  -D,  -e, -f, and -n are unavailable with -h. diff
           does not descend into directories with this option.

     -n    Produces a script similar to -e, but in  the  opposite
           order and with a count of changed lines on each insert
           or delete command.

     -u    Produces a listing of differences with three lines  of
           context.  The  output  is  similar  to  that of the -c
           option, except that the context is "unified".  Removed
           and  changed  lines in file1 are marked by a '-' while
           lines added or changed in file2 are marked by  a  '+'.
           Both  versions  of changed lines appear in the output,
           while added, removed, and context  lines  appear  only
           once.  The  identification  of file1 and file2 is dif-
           ferent, with "---" and "+++" being printed where "***"
           and "---" would appear with the -c option. Each change
           is separated by a line of the form

           @@ -n1,n2 +n3,n4 @@

     -U number
           Produces a listing of differences  identical  to  that
           produced by -u with number lines of context.

     The following options are used for comparing directories:

     -l    Produces output in long format. Before the diff,  each
           text file is piped through pr(1) to paginate it. Other
           differences are remembered and  summarized  after  all
           text file differences are reported.

     -r    Applies  diff  recursively  to  common  subdirectories

     -s    Reports files that are the identical. These  identical
           files would not otherwise be mentioned.

     -S name
           Starts a directory diff in the middle, beginning  with
           the file name.


     The following operands are supported:


     file2 A path name of a file or directory to be compared.  If
           either file1 or file2 is -, the standard input will be
           used in its place.


           A path name of a directory to be compared.

     If only one of file1 and file2 is a directory, diff will  be
     applied  to the non-directory file and the file contained in
     the directory file with a filename that is the same  as  the
     last component of the non-directory file.


     See largefile(5) for the description of the behavior of diff
     when encountering files greater than or equal to 2 Gbyte ( 2
    **31 bytes).


     Example 1: Typical output of the diff command

     In the following command, dir1 is a directory  containing  a
     directory  named  x, dir2 is a directory containing a direc-
     tory named x, dir1/x and dir2/x  both  contain  files  named
     date.out, and dir2/x contains a file named y:

     example% diff -r dir1 dir2
     Common subdirectories: dir1/x and dir2/x

     Only in dir2/x: y

     diff -r dir1/x/date.out dir2/x/date.out


     < Mon Jul  2 13:12:16 PDT 1990


     > Tue Jun 19 21:41:39 PDT 1990


     See environ(5) for descriptions of the following environment
     variables  that  affect the execution of diff: LANG, LC_ALL,

     TZ    Determines the locale for affecting the timezone  used
           for  calculating  file  timestamps written with the -C
           and -c options.


     The following exit values are returned:

     0     No differences were found.

     1     Differences were found.

     >1    An error occurred.


           temporary file used for comparison

           executable file for -h option


     See attributes(5) for descriptions of the  following  attri-

    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    | Availability                | SUNWesu                     |
    | CSI                         | Enabled                     |
    | Interface Stability         | Standard                    |


     bdiff(1), cmp(1), comm(1), dircmp(1), ed(1),  pr(1),  sdiff(
     1), attributes(5), environ(5), largefile(5), standards(5)


     Editing scripts produced under the  -e  or  -f  options  are
     naive  about  creating  lines  consisting of a single period

     Missing NEWLINE at end of file indicates that the last  line
     of the file in question 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.

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