vis
- display non-printable characters in a visual format
SYNOPSIS
[-cbflnostw
]
[-F foldwidth
]
[file ...
]
DESCRIPTION
The
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
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 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-printable characters using C-style backslash sequences.
-F
Causes
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 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,
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.
Due to limitations in the underlying
vis(3)
function, the
utility
does not recognize multibyte characters, and thus may consider them to be
non-printable when they are in fact printable (and vice versa).
