DIFF(1) UNIX Programmer's Manual DIFF(1) NAME diff - differential file and directory comparator SYNOPSIS diff [ -l ] [ -r ] [ -s ] [ -cefhn ] [ -biwt ] dir1 dir2 diff [ -cefhn ] [ -biwt ] file1 file2 diff [ -D_s_t_r_i_n_g ] [ -biw ] file1 file2 DESCRIPTION If both arguments are directories, _d_i_f_f sorts the contents of the directories by name, and then runs the regular file _d_i_f_f algorithm (described below) on text files which are different. Binary files which differ, common subdirec- tories, and files which appear in only one directory are listed. Options when comparing directories are: -l long output format; each text file _d_i_f_f is piped through _p_r(1) to paginate it, other differences are remembered and summarized after all text file differ- ences are reported. -r causes application of _d_i_f_f recursively to common sub- directories encountered. -s causes _d_i_f_f to report files which are the same, which are otherwise not mentioned. -Sname starts a directory _d_i_f_f in the middle beginning with file _n_a_m_e. When run on regular files, and when comparing text files which differ during directory comparison, _d_i_f_f tells what lines must be changed in the files to bring them into agree- ment. Except in rare circumstances, _d_i_f_f finds a smallest sufficient set of file differences. If neither _f_i_l_e_1 nor _f_i_l_e_2 is a directory, then either may be given as `-', in which case the standard input is used. If _f_i_l_e_1 is a direc- tory, then a file in that directory whose file-name is the same as the file-name of _f_i_l_e_2 is used (and vice versa). There are several options for output format; the default output format contains lines of these forms: _n_1 a _n_3,_n_4 _n_1,_n_2 d _n_3 _n_1,_n_2 c _n_3,_n_4 These lines resemble _e_d commands to convert _f_i_l_e_1 into _f_i_l_e_2. The numbers after the letters pertain to _f_i_l_e_2. In fact, by exchanging `a' for `d' and reading backward one may ascertain equally how to convert _f_i_l_e_2 into _f_i_l_e_1. As in Printed 11/26/99 October 21, 1996 1 DIFF(1) UNIX Programmer's Manual DIFF(1) _e_d, identical pairs where _n_1 = _n_2 or _n_3 = _n_4 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 `>'. Except for -b, -w, -i or -t which may be given with any of the others, the following options are mutually exclusive: -e produces a script of _a, _c and _d commands for the editor _e_d, which will recreate _f_i_l_e_2 from _f_i_l_e_1. 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 _e_d scripts ($2,$3,...) made by _d_i_f_f 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 compar- ing directories with -e, so that the result is a _s_h(1) script for converting text files which are common to the two directories from their state in _d_i_r_1 to their state in _d_i_r_2. -f produces a script similar to that of -e, not useful with _e_d, and in the opposite order. -n produces a script similar to that of -e, but in the opposite order and with a count of changed lines on each insert or delete command. This is the form used by _r_c_s_d_i_f_f(1). -c produces a diff with lines of context. The default is to present 3 lines of context and may be changed, e.g to 10, by -c10. With -c the output format is modified slightly: the output beginning with identification of the files involved and their creation dates and then each change is separated by a line with a dozen *'s. The lines removed from _f_i_l_e_1 are marked with `- '; those added to _f_i_l_e_2 are marked `+ '. Lines which are changed from one file to the other are marked in both files with with `! '. Changes which lie within lines of each other are grouped together on output. (This is a change from the previous ``diff -c'' but the resulting output is usually much easier to inter- pret.) Printed 11/26/99 October 21, 1996 2 DIFF(1) UNIX Programmer's Manual DIFF(1) -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. -Dstring causes _d_i_f_f to create a merged version of _f_i_l_e_1 and _f_i_l_e_2 on the standard output, with C preprocessor controls included so that a compilation of the result without defining _s_t_r_i_n_g is equivalent to compiling _f_i_l_e_1, while defining _s_t_r_i_n_g will yield _f_i_l_e_2. -b causes trailing blanks (spaces and tabs) to be ignored, and other strings of blanks to compare equal. -w is similar to -b but causes whitespace (blanks and tabs) to be totally ignored. E.g., ``if ( a == b )'' will compare equal to ``if(a==b)''. -i ignores the case of letters. E.g., ``A'' will com- pare equal to ``a''. -t will expand tabs in output lines. Normal or -c output adds character(s) to the front of each line which may screw up the indentation of the original source lines and make the output listing difficult to interpret. This option will preserve the origi- nal source's indentation. FILES /tmp/d????? /usr/libexec/diffh for -h /bin/diff for directory diffs /bin/pr SEE ALSO cmp(1), cc(1), comm(1), ed(1), diff3(1) DIAGNOSTICS Exit status is 0 for no differences, 1 for some, 2 for trou- ble. 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, _d_i_f_f first compares the files ala _c_m_p, and then decides to run the _d_i_f_f 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 Printed 11/26/99 October 21, 1996 3 DIFF(1) UNIX Programmer's Manual DIFF(1) differences are insignificant blank string or case differ- ences. Printed 11/26/99 October 21, 1996 4