vis(1)

NAME

vis - display non-printable characters in a visual format

SYNOPSIS

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

DESCRIPTION

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 charac

ters except
space, tab, and newline are encoded. 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 dou

bling of backslashes. This produces output which is neither in

vertible 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 se

quence 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
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 un

vis(1).

-o Request a format which displays non-printable char

acters as an

octal number, dd.

-s Only characters considered unsafe to send to a ter

minal are

encoded. This flag allows backspace, bell, and car

riage return
in addition to the default space, tab and newline.

-t Tabs are also encoded.

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

SEE ALSO

unvis(1), vis(3)

HISTORY

The vis command appeared in 4.4BSD.

BUGS

Due to limitations in the underlying vis(3) function, the

vis utility
does not recognize multibyte characters, and thus may con

sider them to be
non-printable when they are in fact printable (and vice ver

sa).

BSD June 25, 2004

BSD