vis - display non-printable characters in a visual format
vis [-cbflnostw] [-F [foldwidth]] [file ...]
vis is a filter for converting non-printable characters into
representation. It differs from cat -v in that the form can
and invertible. By default, all non-printing characters except space,
tab, and newline are encoded, as are any meta-characters
set). A detailed description of the various visual formats
is given in
The options are as follows:
-b Turns off prepending of backslash before up-arrow
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
characters using C-style backslash sequences.
-F Causes vis to fold output lines to foldwidth columns
80), like fold(1), except that a hidden newline sequence is used,
(which is removed when inverting the file back to
form with unvis(1)). If the last character in the
does not end in a newline, a hidden newline sequence
to the output. This makes the output usable with
and other utilities which typically don't work with
-f Same as -F.
-l Mark newlines with the visible sequence `, followed
-n Turns off any encoding, except for the fact that
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,
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.
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.
The vis command appeared in 4.4BSD.
OpenBSD 3.6 April 19, 1994
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