NAME    [Toc]    [Back]

     vis - display non-printable characters in a visual format

SYNOPSIS    [Toc]    [Back]

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

DESCRIPTION    [Toc]    [Back]

     vis is a filter for converting non-printable characters into
a visual
     representation.  It differs from cat -v in that the form can
be unique
     and invertible.  By default, all non-printing characters except space,
     tab,  and  newline  are  encoded, as are any meta-characters
(eighth bit
     set).  A detailed description of the various 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 backslashes.
   This produces output which is neither invertible nor
             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-printable
 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 don't work  with
partial
             lines.

     -f      Same as -F.

     -l       Mark newlines with the visible sequence `, followed
by the
             newline.

     -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, dd.

     -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.
Meta-characters
             that are considered graphic characters by isgraph(3)
are not encoded.


     -t      Tabs are also encoded.

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

SEE ALSO    [Toc]    [Back]

     unvis(1), vis(3)

HISTORY    [Toc]    [Back]

     The vis command appeared in 4.4BSD.

OpenBSD     3.6                          April      19,      1994