display non-printable characters in a visual format
foldwidth] [file ...]
vis 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 vis(3).
The options are as follows:
- Encode all characters, whether originally visible or not.
- 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.
vis to fold output lines to
foldwidth columns, 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
-F, except output is always folded to 80
- 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 is selected. When
combined with the
vis becomes like an invertible version of the
fold(1) utility. That is, the output can
be unfolded by running the output through
- Request a format which displays non-printable characters as an octal
- 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 isgraph(3) are
- Tabs are also encoded.
- White space (space-tab-newline) is also encoded.
vis command appeared in