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VIS(1)                      General Commands Manual                     VIS(1)

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.

EXAMPLES
     Visualize characters encoding white spaces and tabs:

           $ printf "\x10\n\t\n" | vis -w -t
           \^P\012\011\012

     Same as above but using `\$' for newline followed by an actual newline:

           $ printf "\x10\n\t\n" | vis -w -t -l
           \^P\$
           \011\$

     Visualize string using URI encoding:

           $ printf https://www.NetBSD.org | vis -h
           https%3a%2f%2fwww.NetBSD.org

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.

NetBSD 10.99                   February 18, 2021                  NetBSD 10.99