non-printable characters in a visual format
is a filter for converting non-printable
characters into a visual representation. It differs from
in that the form can be unique and
invertible. By default, all non-printing characters except space, tab, and
newline are encoded, as are any meta-characters (eighth bit set). A detailed
description of the various visual formats is given in
The options are as follows:
- Encode all characters, whether originally visible or
- 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 nor 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.
- Causes vis to fold output
lines to foldwidth columns, like
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
- Like -F, except output is
always folded to 80 columns.
- Mark newlines with the visible sequence
\$’, followed by the newline.
- 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
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. Meta-characters that are
considered graphic characters by
- Tabs are also encoded.
- White space (space-tab-newline) is also encoded.
command appeared in