(diff.info.gz) Line Group Formats

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(diff.info.gz) If-then-else

(diff.info.gz) Line Formats

 
 Line Group Formats
 ------------------
 
    Line group formats let you specify formats suitable for many
 applications that allow if-then-else input, including programming
 languages and text formatting languages.  A line group format specifies
 the output format for a contiguous group of similar lines.
 
    For example, the following command compares the TeX files `old' and
 `new', and outputs a merged file in which old regions are surrounded by
 `\begin{em}'-`\end{em}' lines, and new regions are surrounded by
 `\begin{bf}'-`\end{bf}' lines.
 
      diff \
         --old-group-format='\begin{em}
      %<\end{em}
      ' \
         --new-group-format='\begin{bf}
      %>\end{bf}
      ' \
         old new
 
    The following command is equivalent to the above example, but it is a
 little more verbose, because it spells out the default line group
 formats.
 
      diff \
         --old-group-format='\begin{em}
      %<\end{em}
      ' \
         --new-group-format='\begin{bf}
      %>\end{bf}
      ' \
         --unchanged-group-format='%=' \
         --changed-group-format='\begin{em}
      %<\end{em}
      \begin{bf}
      %>\end{bf}
      ' \
         old new
 
    Here is a more advanced example, which outputs a diff listing with
 headers containing line numbers in a "plain English" style.
 
      diff \
         --unchanged-group-format='' \
         --old-group-format='-------- %dn line%(n=1?:s) deleted at %df:
      %<' \
         --new-group-format='-------- %dN line%(N=1?:s) added after %de:
      %>' \
         --changed-group-format='-------- %dn line%(n=1?:s) changed at %df:
      %<-------- to:
      %>' \
         old new
 
    To specify a line group format, use `diff' with one of the options
 listed below.  You can specify up to four line group formats, one for
 each kind of line group.  You should quote FORMAT, because it typically
 contains shell metacharacters.
 
 `--old-group-format=FORMAT'
      These line groups are hunks containing only lines from the first
      file.  The default old group format is the same as the changed
      group format if it is specified; otherwise it is a format that
      outputs the line group as-is.
 
 `--new-group-format=FORMAT'
      These line groups are hunks containing only lines from the second
      file.  The default new group format is same as the changed group
      format if it is specified; otherwise it is a format that outputs
      the line group as-is.
 
 `--changed-group-format=FORMAT'
      These line groups are hunks containing lines from both files.  The
      default changed group format is the concatenation of the old and
      new group formats.
 
 `--unchanged-group-format=FORMAT'
      These line groups contain lines common to both files.  The default
      unchanged group format is a format that outputs the line group
      as-is.
 
    In a line group format, ordinary characters represent themselves;
 conversion specifications start with `%' and have one of the following
 forms.
 
 `%<'
      stands for the lines from the first file, including the trailing
      newline.  Each line is formatted according to the old line format
      ( Line Formats).
 
 `%>'
      stands for the lines from the second file, including the trailing
      newline.  Each line is formatted according to the new line format.
 
 `%='
      stands for the lines common to both files, including the trailing
      newline.  Each line is formatted according to the unchanged line
      format.
 
 `%%'
      stands for `%'.
 
 `%c'C''
      where C is a single character, stands for C.  C may not be a
      backslash or an apostrophe.  For example, `%c':'' stands for a
      colon, even inside the then-part of an if-then-else format, which
      a colon would normally terminate.
 
 `%c'\O''
      where O is a string of 1, 2, or 3 octal digits, stands for the
      character with octal code O.  For example, `%c'\0'' stands for a
      null character.
 
 `FN'
      where F is a `printf' conversion specification and N is one of the
      following letters, stands for N's value formatted with F.
 
     `e'
           The line number of the line just before the group in the old
           file.
 
     `f'
           The line number of the first line in the group in the old
           file; equals E + 1.
 
     `l'
           The line number of the last line in the group in the old file.
 
     `m'
           The line number of the line just after the group in the old
           file; equals L + 1.
 
     `n'
           The number of lines in the group in the old file; equals L -
           F + 1.
 
     `E, F, L, M, N'
           Likewise, for lines in the new file.
 
      The `printf' conversion specification can be `%d', `%o', `%x', or
      `%X', specifying decimal, octal, lower case hexadecimal, or upper
      case hexadecimal output respectively.  After the `%' the following
      options can appear in sequence: a series of zero or more flags; an
      integer specifying the minimum field width; and a period followed
      by an optional integer specifying the minimum number of digits.
      The flags are `-' for left-justification, `'' for separating the
      digit into groups as specified by the `LC_NUMERIC' locale category,
      and `0' for padding with zeros instead of spaces.  For example,
      `%5dN' prints the number of new lines in the group in a field of
      width 5 characters, using the `printf' format `"%5d"'.
 
 `(A=B?T:E)'
      If A equals B then T else E.  A and B are each either a decimal
      constant or a single letter interpreted as above.  This format
      spec is equivalent to T if A's value equals B's; otherwise it is
      equivalent to E.
 
      For example, `%(N=0?no:%dN) line%(N=1?:s)' is equivalent to `no
      lines' if N (the number of lines in the group in the the new file)
      is 0, to `1 line' if N is 1, and to `%dN lines' otherwise.
 

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(diff.info.gz) If-then-else

(diff.info.gz) Line Formats