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VIS(1)                  FreeBSD General Commands Manual                 VIS(1)

     vis -- display non-printable characters in a visual format

     vis [-cbflnostw] [-F foldwidth] [file ...]

     The vis utility is a filter for converting non-printable characters into
     a visual representation.  It differs from `cat -v' in that the form is
     unique and invertible.  By default, all non-graphic characters except
     space, tab, and newline are encoded.  A detailed description of the vari-
     ous visual formats is given in vis(3).

     The options are as follows:

     -b      Turns off prepending of backslash before up-arrow control
             sequences and meta characters, and disables the doubling of back-
             slashes.  This produces output which is neither invertible or
             precise, but does represent a minimum of change to the input.  It
             is similar to ``cat -v''.

     -c      Request a format which displays a small subset of the non-print-
             able characters using C-style backslash sequences.

     -F      Causes vis to fold output lines to foldwidth columns (default
             80), like fold(1), except that a hidden newline sequence is used,
             (which is removed when inverting the file back to its original
             form with unvis(1)).  If the last character in the encoded file
             does not end in a newline, a hidden newline sequence is appended
             to the output.  This makes the output usable with various editors
             and other utilities which typically do not work with partial

     -f      Same as -F.

     -l      Mark newlines with the visible sequence `\$', followed by the

     -n      Turns off any encoding, except for the fact that backslashes are
             still doubled and hidden newline sequences inserted if -f or -F
             is selected.  When combined with the -f flag, vis becomes like an
             invertible version of the fold(1) utility.  That is, the output
             can be unfolded by running the output through unvis(1).

     -o      Request a format which displays non-printable characters as an
             octal number, \ddd.

     -s      Only characters considered unsafe to send to a terminal are
             encoded.  This flag allows backspace, bell, and carriage return
             in addition to the default space, tab and newline.

     -t      Tabs are also encoded.

     -w      White space (space-tab-newline) is also encoded.

     unvis(1), vis(3)

     The vis command appeared in 4.4BSD.

     Due to limitations in the underlying vis(3) function, the vis utility
     does not recognize multibyte characters, and thus may consider them to be
     non-printable when they are in fact printable (and vice versa).

FreeBSD 6.2                      June 25, 2004                     FreeBSD 6.2


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