NAME
vis —
display non-printable characters
in a visual format
SYNOPSIS
vis |
[-bcfhlMmNnoSstw]
[-e extra]
[-F
foldwidth]
[file ...] |
DESCRIPTION
vis 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
”.
(VIS_NOSLASH
)
-
-
- -c
- Request a format which displays a small subset of the
non-printable characters using C-style backslash sequences.
(
VIS_CSTYLE
)
-
-
- -e
extra
- Also encode characters in extra, per
svis(3).
-
-
- -F
foldwidth
- 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.
-
-
- -h
- Encode using the URI encoding from RFC 1808.
(
VIS_HTTPSTYLE
)
-
-
- -l
- Mark newlines with the visible sequence
‘
\$
’, followed by the newline.
-
-
- -M
- Encode all shell meta characters (implies
-S, -w, -g)
(
VIS_META
)
-
-
- -m
- Encode using the MIME Quoted-Printable encoding from RFC
2045. (
VIS_MIMESTYLE
)
-
-
- -N
- Turn on the
VIS_NOLOCALE
flag which
encodes using the “C” locale, removing any encoding
dependencies caused by the current locale settings specified in the
environment.
-
-
- -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. (
VIS_OCTAL
)
-
-
- -S
- Encode shell meta-characters that are non-white space or
glob. (
VIS_SHELL
)
-
-
- -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.
(
VIS_SAFE
)
-
-
- -t
- Tabs are also encoded.
(
VIS_TAB
)
-
-
- -w
- White space (space-tab-newline) is also encoded.
(
VIS_WHITE
)
MULTIBYTE CHARACTER SUPPORT
vis supports multibyte character input. The encoding
conversion is influenced by the setting of the
LC_CTYPE
environment variable which defines the set of
characters that can be copied without encoding.
When 8-bit data is present in the input,
LC_CTYPE
must
be set to the correct locale or to the C locale. If the locales of the data
and the conversion are mismatched, multibyte character recognition may fail
and encoding will be performed byte-by-byte instead.
ENVIRONMENT
-
-
LC_CTYPE
- Specify the locale of the input data. Set to C if the input
data locale is unknown.
SEE ALSO
unvis(1),
svis(3),
vis(3)
HISTORY
The
vis command appears in
4.4BSD.
Multibyte character support was added in
NetBSD 7.0
and
FreeBSD 9.2.