diff - display differences between two files (or directories)

diff [options] old-file new-file

Use - to read from standard input. As a special case, diff - - compares a copy of standard input to itself.

diff directory file
  Compares the corresponding file in directory . The non-directory file must not be - .

diff directory directory
 Compares corresponding files in both directories, in alphabetical order.
This comparison is not recursive unless the -r or ‑‑recursive option is given.
diff never compares the actual contents of a directory as if it were a file. The file that is fully specified may not be standard input, because standard input is nameless and the notion of "file with the same name" does not apply.

Use -- to terminate options when specifing file names which begin with a -.

Multiple single letter options can be combined (example: ‑wyW50)

-i,--ignore-case
-B,--ignore-blank-lines Ignore changes that just insert or delete Blank lines.
-b,--ignore-space-change Ignore changes in amount of blanks.
-w,--ignore-all-space Ignore white space when comparing lines.
-q --brief Do not show differences. quite only whether the files differ, not the details of the differences. Check the return code $?

-I regexp,
--ignore-matching-lines= regexp Ignore changes that just insert or delete lines that match regexp.
-d, --minimal, Change the algorithm to perhaps find a smaller set of changes. slower (sometimes much slower).
-H,
--speed-large-files Use Heuristics to speed handling of large files that have numerous scattered small changes.

--side-by-side, -y 
  diff -y /tmp/dfdf /tmp/dfdf_1
Avail   Mounted                                                 Avail   Mounted
695M    /                                                       695M    /
170M    /Volumes/DATA                                           170M    /Volumes/DATA
56K     /Volumes/BACKUP_2                                       56K     /Volumes/BACKUP_2
919M    /Volumes/TBD                                          | 898M    /Volumes/TBD
xxxx                                                            xxxx
-W columns,
--width=columns 
   diff -yW70 /tmp/dfdf /tmp/dfdf_1
Avail   Mounted                         Avail   Mounted
695M    /                               695M    /
170M    /Volumes/DATA                   170M    /Volumes/DATA
56K     /Volumes/BACKUP_2               56K     /Volumes/BACKUP_2
919M    /Volumes/TBD              |     898M    /Volumes/TBD
xxxx                                    xxxx
--suppress-common-lines 
diff  -wyW$COLUMNS --su    /tmp/dfdf /tmp/dfdf_1

919M    /Volumes/TBD                                         | 898M    /Volumes/TBD

diff -yW50 --suppress /tmp/dfdf /tmp/dfdf_1
919M                                                   |  898M
--leftcolumn only 
diff -yW60 --left /tmp/dfdf /tmp/dfdf_1
Avail   Mounted              (
695M    /                    (
170M    /Volumes/DATA        (
56K     /Volumes/BACKUP_2    (
919M    /Volumes/TBD         |  898M    /Volumes/TBD
xxxx                         (

When comparing directories:
-s,
--report-identical-files 		Report are identical when files are the same,
     otherwise no output is produced.
-x pattern ,
--exclude=pattern 		ignore files and subdirectories whose basenames match pattern.
--exclude-from=file ignore files and subdirectories whose basenames match any pattern in file.
-X file ignore files and subdirectories whose basenames match any pattern contained in file.
-r,
--recursive 		compare subdirectories .
-N,
--new-file		 a file found in only in one directory is compared to an empty file.
-P,
--unidirectional-new-file		 a file occuring only in the second directory id compared to an empty file.
-S file ,
--starting-file=file 		start with the file file. Use for resuming an aborted comparison.

  -c Use the context output format, i.e. show the differences with some lines before and after.
  -C lines,
--context=lines. show lines of context. Default 3. 

diff  -c /tmp/dfdf /tmp/dfdf_1
*** /tmp/dfdf   Tue Sep  5 18:10:15 2006
--- /tmp/dfdf_1 Tue Sep  5 18:10:24 2006
***************
*** 4,7 ****
  1.3G  /Volumes/PHOTOS_1
  2.7G  /Volumes/PHOTOS_2
  56K   /Volumes/BACKUP_2
! 919M  /Volumes/TBD
--- 4,7 ----
  1.3G  /Volumes/PHOTOS_1
  2.7G  /Volumes/PHOTOS_2
  56K   /Volumes/BACKUP_2
! 898M  /Volumes/TBD

  -e,
--ed Make output that is a valid ed script.

diff  -e /tmp/dfdf /tmp/dfdf_1
7c
898M    /Volumes/TBD
.


       

  -f,
 --forward-ed Make output that looks vaguely like an ed script but has changes in the order they appear in the file.
diff  -f /tmp/dfdf /tmp/dfdf_1
c7
898M    /Volumes/TBD
.




  -F regexp In context and unified format, for  each  hunk  of  differences, show some of the last preceding line that matches regexp.  


  -n,
 --rcs  Output RCS-format(Revision Control Systems) diffs; like -f except that each command specifies the number of lines affected.  


diff  -n /tmp/dfdf /tmp/dfdf_1
d7 1
a7 1
898M    /Volumes/TBD


       

  -L label,
 --label=label
	      Use label instead of the file name in  the  context  and unified format headers.








-D name,
 --ifdef=name Make  merged if-then-else format output, conditional on the preprocessor macro name.


--line-format=format Use format to output all input lines in in-then-else format.  


%L contents of line      %l  , excluding any trailing newline

%[-]*[width][.[prec*{doxX}*n  printf-style spec for input line number

%%  the % character

x  the single character x  (i.e. any character)

%c'\OOO'  the character with octal code OOO



diff --line-format="%8dn  %L" /tmp/dfdf /tmp/dfdf_1

       1  Avail Mounted
       2  695M  /
       3  170M  /Volumes/DATA
       4  1.3G  /Volumes/PHOTOS_1
       5  2.7G  /Volumes/PHOTOS_2
       6  56K   /Volumes/BACKUP_2
       7  919M  /Volumes/TBD
       7  898M  /Volumes/TBD
       8  xxxx




--old-line-format=format... a line taken from just the  first  file  

--new-line-format=format ...a line taken from just the second  file  

--unchanged-line-format=format ... a line common to both files 



%  lines from FILE1

%>  lines from FILE2

%=  lines common to FILE1 and FILE2

%%  %

%c'C'  the single character C

%c'\OOO'  the character with octal code OOO

%[-][WIDTH][.[PREC]]{doxX}LETTER  printf-style spec for LETTER

LETTERs are as follows for new group, lower case for old group:

F  first line number

L  last line number

N  number of lines = L-F+1

E  F-1

M  L+1 

--changed-group-format=format Use  format to  output  a line group containing differing lines from both files 

--old-group-format=format ... the first file 

--new-group-format=format ...the second 

--unchanged-group-format=format ... of common lines from both files 




       



-u     Use the unified output format.

-U  lines,
 --unified[=lines] Use  the unified output format, showing lines of context. default 3. 




#cat 0

Avail   Mounted
10632   /
791     /Volumes/DATA
560     /Volumes/PHOTOS
3504    /Volumes/BACKUPS
4542    /Volumes/linux
934     /Volumes/SWAP

#cat 00

Avail   Mounted
10639   /
791     /Volumes/DATA
560     /Volumes/PHOTOS
3504    /Volumes/BACKUPS
4542    /Volumes/linux
934     /Volumes/SWAP





diff -u 0 00
--- 0   2007-01-14 21:07:11.000000000 -0500
+++ 00  2007-01-14 21:15:54.000000000 -0500
@@ -1,5 +1,5 @@
 Avail  Mounted
-10632  /
+10639  /
 791    /Volumes/DATA
 560    /Volumes/PHOTOS
 3504   /Volumes/BACKUPS











-p,
 --show-c-function 

--show-function-line=regexp
In context and unified format, for  each  hunk  of  differences,
              show some of the last preceding line that matches regexp.






--horizon-lines=lines Do not discard the last lines lines of the common prefix and the first lines lines of the common suffix.


-t,
 --expand-tabs 		to spaces in the output, to preserve the alignment of tabs in the input files.


-T,
 --initial-tab  		Output a Tab rather than a space before the text of  a  line  in
	      normal  or context format.  This causes the alignment of tabs in the line to look normal.
   
--from-file= file Compare file to all operands.  file can be a directory.

   
--to-file= file Compare all operands to file. file can be a directory.

-l, --paginate Pass the output through pr to paginate it.



-a, --text Treat  all  files as ASCII text and compare them line-by-line, even if they do not seem to be text. 


   
-v, --version 


    --sdiff-merge-assist
              Print extra information to help sdiff.  sdiff uses  this  option
              when it runs diff.  This option is not intended for users to use directly.




See 

       cmp , comm, diff3(1), ed(1), patch(1), pr(1), sdiff(1).
       

DIAGNOSTICS exit status 

 0 no differences were found, 1 some differences were found, and 2 means trouble ( file not found/accessible,...).






 


cmp options  file1 file2 





 -b
 --print-bytes 		output differing bytes.

-i SKIP
 --ignore-initial=SKIP 		Skip the first SKIP bytes of input.

-i SKIP1:SKIP2
 --ignore-initial=SKIP1:SKIP2
                		    Skip the first SKIP1 bytes of FILE1 and
                     the first  bytes of FILE2.

-l
 --verbose 		Output byte numbers and values of all differing bytes.

-n LIMIT
 --bytes=LIMIT 		Compare at most LIMIT bytes.

-s
 --quiet
 --silent 		Output nothing; test the return value

-v
 --version		 

--help 



Return values:  0 - files are identical; 1 - files differ; 2 - inaccessible or missing argument











comm [OPTION]... FILE1 FILE2


Compare sorted files FILE1 and FILE2 line by line displaying lines in common.



With  no  options,  produce three-column output.  

first Column contains lines unique to FILE1, 

second column contains lines unique to FILE2 and 

last column contains lines common to both files.

 
-1     suppress lines unique to FILE1 (first column) 

-2     suppress lines unique to FILE2  (secondcolumn)

-3     suppress lines that appear in both files (last column)




--help 

--version output version information and exit


> cat 1
aaaaaaaaa
bbbbbbbb
ccccccc
> cat 2
aaaaaaaaa
b222bbbb
ccccccc
> comm 1 2
                aaaaaaaaa
        b222bbbb
bbbbbbbb
                ccccccc







diff