[](https://github.com/tecolicom/App-cat-v/actions) [](https://metacpan.org/release/App-cat-v)
# NAME
cat-v - visualize non-printing characters
# SYNOPSIS
cat-v \[ options \] args ...
OPTIONS
-n --reset Disable all character conversion
-c --visible=# Specify visualize characters
-r --repeat=# Specify repeat characters
-R --replicate Replicate original line as is
-t --expand[=#] Expand tabs
-T --no-expand Do not expand tabs
--ts --tabstyle=# Set tab style
--tabstop=# Set tab width
--tabhead=# Set tab-head character
--tabspace=# Set tab-space character
-h --help Print this message
-v --version Print version
OPTIONS FOR EACH CHARACTERS
--esc Enable escape
--esc=c Show escape in control format
--esc=+c Show escape in control format and reproduce
--nl=0 Disable newline
--sp=~ Convert spaces to tilde
--sp='OPEN BOX' Unicode name
--esc=+U+035B Unicode code point
# VERSION
Version 1.01
# DESCRIPTION
The `cat -v` command is often used to display characters that cannot
be displayed, but is not always suitable for viewing the output of
modern applications because it converts all non-ASCII characters.
The `cat-v` command visualizes whitespace and control characters
while preserving the display of displayable graphic characters.
Also, by default, escape characters are not converted, so decorations
by ANSI escape sequences are retained.
Sometimes it is desirable to visualize whitespace characters. The
`cat -t` command can visualize tab characters, but the problem is
that it breaks the visual format. We may want to see which parts are
tabs and which parts are space characters while preserving the format.
Extra whitespace characters at the end of a line can also be noticed
by visualizing them.
Using `cat-v`, tab characters are visualized in such a way that the
space on the display does not change.
Control characters can be displayed in control format and Unicode
symbol characters. By default, control characters other than newline
and escape characters are displayed as corresponding Unicode symbols.
The second field is the default action. `s` stands for symbol, `m`
for Unicode mark, and `0` for no conversion.
nul s \000 \x{2400} ␀ SYMBOL FOR NULL
soh s \001 \x{2401} ␁ SYMBOL FOR START OF HEADING
stx s \002 \x{2402} ␂ SYMBOL FOR START OF TEXT
etx s \003 \x{2403} ␃ SYMBOL FOR END OF TEXT
eot s \004 \x{2404} ␄ SYMBOL FOR END OF TRANSMISSION
enq s \005 \x{2405} ␅ SYMBOL FOR ENQUIRY
ack s \006 \x{2406} ␆ SYMBOL FOR ACKNOWLEDGE
bel s \007 \x{2407} ␇ SYMBOL FOR BELL
bs s \010 \x{2408} ␈ SYMBOL FOR BACKSPACE
ht s \011 \x{2409} ␉ SYMBOL FOR HORIZONTAL TABULATION
nl m \012 \x{240A} ␊ SYMBOL FOR LINE FEED
vt s \013 \x{240B} ␋ SYMBOL FOR VERTICAL TABULATION
np m \014 \x{240C} ␌ SYMBOL FOR FORM FEED
cr s \015 \x{240D} ␍ SYMBOL FOR CARRIAGE RETURN
so s \016 \x{240E} ␎ SYMBOL FOR SHIFT OUT
si s \017 \x{240F} ␏ SYMBOL FOR SHIFT IN
dle s \020 \x{2410} ␐ SYMBOL FOR DATA LINK ESCAPE
dc1 s \021 \x{2411} ␑ SYMBOL FOR DEVICE CONTROL ONE
dc2 s \022 \x{2412} ␒ SYMBOL FOR DEVICE CONTROL TWO
dc3 s \023 \x{2413} ␓ SYMBOL FOR DEVICE CONTROL THREE
dc4 s \024 \x{2414} ␔ SYMBOL FOR DEVICE CONTROL FOUR
nak s \025 \x{2415} ␕ SYMBOL FOR NEGATIVE ACKNOWLEDGE
syn s \026 \x{2416} ␖ SYMBOL FOR SYNCHRONOUS IDLE
etb s \027 \x{2417} ␗ SYMBOL FOR END OF TRANSMISSION BLOCK
can s \030 \x{2418} ␘ SYMBOL FOR CANCEL
em s \031 \x{2419} ␙ SYMBOL FOR END OF MEDIUM
sub s \032 \x{241A} ␚ SYMBOL FOR SUBSTITUTE
esc 0 \033 \x{241B} ␛ SYMBOL FOR ESCAPE
fs s \034 \x{241C} ␜ SYMBOL FOR FILE SEPARATOR
gs s \035 \x{241D} ␝ SYMBOL FOR GROUP SEPARATOR
rs s \036 \x{241E} ␞ SYMBOL FOR RECORD SEPARATOR
us s \037 \x{241F} ␟ SYMBOL FOR UNIT SEPARATOR
sp m \040 \x{2420} ␠ SYMBOL FOR SPACE
del s \177 \x{2421} ␡ SYMBOL FOR DELETE
nbsp s \240 \x{2423} ␣ OPEN BOX
At this time, Unicode markings are available for the following
characters
nul \x{2205} ∅ EMPTY SET
bel \x{237E} ⍾ BELL SYMBOL
nl \x{23CE} ⏎ RETURN SYMBOL
np \x{2398} ⎘ NEXT PAGE
sp \x{00B7} · MIDDLE DOT
del \x{232B} ⌫ ERASE TO THE LEFT
# OPTIONS
- **-n**, **--reset**
Disables all character conversions and resets repeat characters.
- **-c**, **--visible** _name_=_flag_,...
Give the character type and flags as parameters to specify the
character to be visualized and the conversion format.
c control style
s symbol style
m Unicode mark (if exists)
0 do not convert
* non-alphanumeric char is used as a replacement
Option `-c nl=1` can also be used to visualize newline characters.
For newline characters only, after displaying the result of the
conversion, the original character is output at the same time.
Use the names in the list above to specify by character type. If you
want to convert escapes without converting tabs, use the following
cat-v -c tab=0 -c esc=s
Multiple items can be specified at the same time. The following
example sets `tab` and `bel` to 0 and `esc` to `s`.
cat-v -c tab=bel=0,esc=s
If `all` is specified for the name, the value applies to all
character types. The following command sets all characters to `s`,
then sets `nl`, `nl`, `np`, and `sp` to `m` and disables `esc`.
This is the default state.
cat-v -c all=s,nul=nl=np=sp=m,esc=0
- **--**_name_\[=_replacement_\]
All control characters can also be accessed by an option with their
name. For example, option `--nl` is defined for the newline
character.
Used alone, it activates the visibility of the character.
cat-v --nl
To disable, give the value 0.
cat-v --nl=0
If a letter other than an alphabet or a number is given, it will be
replaced by that letter.
cat-v --nl='$'
If a string of two or more characters is given, it is interpreted as a
Unicode character name.
cat-v --nl='RETURN SYMBOL' --sp='MIDDLE DOT'
If flag begins with `+`, that character is added to the repeat list.
cat-v --esc=+s
So the above command will have the same meaning as if you had written
as following.
cat-v --esc=s --repeat +esc
- **--repeat**=_name_\[,_name_...\]
Specifies the character type for outputting the original character at
the same time as the converted character. The default setting is
`nl,np`. The following will correctly output the original ANSI
sequence with the escape character visualized.
cat-v -c esc --repeat esc,nl
If _name_ begins with `+`, add that character in addition to the
existing configuration.
cat-v -c esc --repeat +esc
- **-R**, **--replicate**
Before printing the converted string, first output the original
string.
- **-t**\[_n_\], **--expand**\[=_n_\]
- **-T**, **--no-expand**
Tab characters are expanded by default. To explicitly disable it, use
the **-T** or **--no-expand** option.
If an optional number is given for the **-t** option, it is treated as
a tab width. The following two commands are equivalent:
cat-v -t4
cat-v -t --tabstop=4
By default, the style `needle` is applied, which can be changed with
`--tabstyle`. If the `--tabstyle` option is specified with no
arguments, a list of available styles is displayed.
You can disable tab expansion by default by putting the following
setting in your `~/.cat-vrc` file.
option default --no-expand
In such cases, tab expansion can be temporarily enabled by the `-t`
option.
- **--tabstop**=# (DEFAULT: 8)
Set tab width.
- **--tabhead**=#
- **--tabspace**=#
Set tab head and following space characters. If the option value is
longer than single character, it is evaluated as unicode name.
- **--tabstyle**, **--ts**
- **--tabstyle**=_style_, **--ts**=...
- **--tabstyle**=_head-style_,_space-style_ **--ts**=...
Set the style how tab is expanded. Select `symbol` or `shade` for
example. If two style names are combined, like
`squat-arrow,middle-dot`, use `squat-arrow` for tabhead and
`middle-dot` for tabspace.
Show available style list if called without parameter. Styles are
defined in [Text::ANSI::Fold](https://metacpan.org/pod/Text%3A%3AANSI%3A%3AFold) library.
# INSTALL
## CPANMINUS
From CPAN archive:
cpanm App::cat::v
From GIT repository:
cpanm https://github.com/tecolicom/App-cat-v.git
# SEE ALSO
- [https://github.com/tecolicom/App-cat-v.git](https://github.com/tecolicom/App-cat-v.git)
Git repository.
- [App::optex::util::filter](https://metacpan.org/pod/App%3A%3Aoptex%3A%3Autil%3A%3Afilter)
The predecessor of the `cat-v` command was originally created as the
filter module of the [App::optex](https://metacpan.org/pod/App%3A%3Aoptex) command.
# AUTHOR
Kazumasa Utashiro
# LICENSE
Copyright © 2024 Kazumasa Utashiro.
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
