display non-printable characters in a visual
is a filter for converting non-printable
characters into a visual representation. It differs from
’ 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
The options are as follows:
- 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
- Request a format which displays a small subset of the non-printable
characters using C-style backslash sequences.
- Also encode characters in extra, per
vis to fold output lines to
foldwidth columns (default 80), like
except that a hidden newline sequence is used, (which is removed when
inverting the file back to its original form with
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.
- Same as
- Encode using the URI encoding from RFC 1808.
- Mark newlines with the visible sequence
\$’, followed by the newline.
- Encode using the MIME Quoted-Printable encoding from RFC 2045.
- Turns off any encoding, except for the fact that backslashes are still
doubled and hidden newline sequences inserted if
-F is selected. When combined with the
vis becomes like an invertible version
utility. That is, the output can be unfolded by running the output through
- Request a format which displays non-printable characters as an octal
number, \ddd. (
- 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.
- Tabs are also encoded. (
- White space (space-tab-newline) is also encoded.
supports multibyte character input. The
encoding conversion is influenced by the setting of the
environment variable which defines
the set of characters that can be copied without encoding.
When 8-bit data is present in the input,
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.
- Specify the locale of the input data. Set to C if the input data locale is
command appears in
. Myltibyte character support was added in