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VIS(1) NetBSD General Commands Manual VIS(1)
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by Kimmo Suominen.
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vis -- display non-printable characters in a visual format
vis [-bcfhlMmNnoSstw] [-e extra] [-F foldwidth] [file ...]
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 back-
slashes. 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-print-
able characters using C-style backslash sequences. (VIS_CSTYLE)
Also encode characters in extra, per svis(3).
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
-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
-M Encode all shell meta characters (implies -S, -w, -g) (VIS_META)
-m Encode using the MIME Quoted-Printable encoding from RFC 2045.
-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.
-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 cor-
rect locale or to the C locale. If the locales of the data and the con-
version are mismatched, multibyte character recognition may fail and
encoding will be performed byte-by-byte instead.
LC_CTYPE Specify the locale of the input data. Set to C if the input
data locale is unknown.
Visualize characters encoding white spaces and tabs:
$ printf "\x10\n\t\n" | vis -w -t
Same as above but using `\$' for newline followed by an actual newline:
$ printf "\x10\n\t\n" | vis -w -t -l
Visualize string using URI encoding:
$ printf https://www.NetBSD.org | vis -h
unvis(1), svis(3), vis(3)
The vis command appears in 4.4BSD. Multibyte character support was added
in NetBSD 7.0 and FreeBSD 9.2.
NetBSD 9.99 February 18, 2021 NetBSD 9.99