ctpv/doc/ctpv.1

'\" t
.ds ub \(:Uberzug
.
.TH CTPV 1 2022 Linux "User's Reference Manuals"
.
.SH NAME
ctpv \- terminal previewer
.
.SH SYNOPSIS
.
.SY ctpv
.I file
.RI [ w ]
.RI [ h ]
.RI [ x ]
.RI [ y ]
.RI [ id ]
.YS
.
.SY ctpv
.B \-l
.YS
.
.SY ctpv
.B \-m
.IR file \&.\|.\|.\&
.YS
.
.SY ctpv
.RB { \-s | \-c | \-e }
.I id
.YS
.
.SH DESCRIPTION
.
.B ctpv
is a previewer utility made for integration into other programs like
.IR lf .
.
.PP
When
.B ctpv
is given a
.IR file ,
it determines an appropriate preview for it and runs it.
Depending on the preview and installed programs, it can print
some text to standard output or display an image.
Symbolic links are dereferenced.
.
.SS Built-in previews and dependencies
.
Previewing each file type requires specific programs.
If a program is not found on the system,
.B ctpv
will try to use another one.
Only one program is required for each file type.
For example, you only need either
.IR elinks ,
.IR lynx
or
.IR w3m
installed on your system to view HTML files.
.
.\" This table is auto generated!
.
.\" TABLESTART
.TS
allbox;
lb lb
l li .
File type	Programs
any	T{
exiftool cat
T}
archive	T{
atool
T}
diff	T{
colordiff delta diff\-so\-fancy
T}
directory	T{
ls
T}
font	T{
fontimage
T}
gpg-encrypted	T{
gpg
T}
html	T{
elinks lynx w3m
T}
image	T{
ueberzug chafa
T}
json	T{
jq
T}
markdown	T{
mdcat
T}
office	T{
libreoffice
T}
pdf	T{
pdftoppm
T}
text	T{
bat cat highlight source-highlight
T}
torrent	T{
transmission\-show
T}
video	T{
ffmpegthumbnailer
T}
.TE
.\" TABLEEND
.
.SS Integration
.
.TP
\fIlf\fP file manager
Add this snippet to
.I lf
configuration file (usually located at
.IR \(ti/.config/lf/lfrc ).
.
.RS 4
.IP
.EX
set previewer ctpv
set cleaner ctpvclear
&ctpv \-s $id
&ctpvquit $id
.EE
.RE
.
.SS Image previews
.
Image previews are enabled by either installing
.I \*(ub
or
.I Chafa
(as seen in
.IR "Built-in previews and dependencies" )
or using built-in image preview functionality of
.I Kitty
terminal.
.
.PP
When possible,
.B ctpv
will prefer
.I \*(ub
over others image preview methods. You can override this
behavior by using
.B forcekitty
or
.B forcechafa
options (see
.IR "Preview options" ).
.
.SS How previews are selected
.
Initially,
.B ctpv
retrieves MIME type and extension from
.I file
passed as the first argument (MIME type is extracted using
.BR libmagic (3)).
.
.PP
Then it creates a list of all previews respecting user
configuration in a special order, where previews that are
more specific appear at the top and more generic ones at the bottom.
The list can be viewed by using
.B \-l
option. The order can be changed (see
.IR "Setting priority" ).
.
.PP
Finally,
.B ctpv
goes through the list starting with the first element
and checks if a preview matches
.IR file 's
extension and MIME type.
If it does, it runs a preview script.
If the script exits with status 127
(which usually means that a program that is necessary for generating
a preview content is not installed on the system),
.B ctpv
attempts to run another appropriate preview and so on.
If the script exists with 0 or a any other status, both standard output
and standard error are printed.
.
.SH OPTIONS
.
.TP
.B \-l
List all previews.
.
.TP
\fB\-m\fP \fIfile\fP.\|.\|.\&
Print extension and MIME type of
.IR file .
.
.TP
\fB\-s\fP \fIid\fP
Start server with ID
.IR id .
.
.TP
\fB\-c\fP \fIid\fP
Send
.B clear
command to server with ID
.I id
(usually, it removes image from terminal).
.
.TP
\fB\-e\fP \fIid\fP
Kill server with ID
.IR id .
.
.SH CONFIGURATION
.
.B ctpv
uses a configuration file usually located at
.IR \(ti/.config/ctpv/config
(see
.IR FILES ).
Its format somewhat resembles one used by
.IR lf .
There are several commands that can be used to add
previews or set different settings.
Commands are separated by newlines.
Comments start with number sign
.RB \(lq # \(rq.
.
.PP
Example:
.
.IP
.EX
# Set an option
set forcekitty
\~
# Add a new preview
preview cow .moo {{
\&    cowsay < "$f"
}}
\~
# Remove some previews
remove w3m
remove lynx
remove elinks
.EE
.
.SS Preview options
.
An option can be set using
.B set
command.
.
.TP
.B forcekitty
Always use
.I Kitty
terminal's built-in method of previewing images.
.
.TP
.B forcekittyanim
Always use
.I Kitty
terminal's built-in method of previewing images for animated
images.
.
.TP
.B forcechafa
Always use
.I Chafa
for image previews.
.
.TP
.B noimages
Print only text and do not use any image previewing method.
.
.TP
.B nosymlinkinfo
Do not print resolved path of symbolic links.
.
.TP
.B showgpg
Preview
.BR gpg (1)
encrypted files.
Filename must have \(lq.gpg\(rq extension.
.
.SS Defining custom previews
.
User-defined previews are added with
.B preview
command.
.
.PP
An example below defines a new preview with name \(lqmanpage\(rq
that applies to files with extension \(lq.1\(rq.
A preview itself is a shell script enclosed within double curly
braces.
.
.IP
.EX
preview manpage .1 {{
\&    groff \-man \-tep \-Tutf8 \-rLL="${w}n" "${f}" | col \-x
}}
.EE
.
.PP
Running
.I "ctpv\ file.1"
where
.I file.1
is a source code for a manpage will run
.BR groff (1)
to produce a formatted manpage like the one you are reading.
.
.PP
Manpages filenames may also end with other extensions:
\(lq.2\(rq, \(lq.3\(rq, \(lq.4\(rq and so on.
It's possible to make user-defines previews apply to several
file types at once:
.
.IP
.EX
preview manpage .1 .2 .3 .4 .5 .6 .7 .8 {{
\&    # groff command
}}
.EE
.
.PP
Variable
.B $f
stores
.IR file
that was passed as a first argument to
.BR ctpv .
It's strongly suggested to enclose
.B $f
with double quotes
.RB ( \(dq$f\(dq )
because otherwise the script will not work as
expected if
.B $f
stores a filename with whitespace.
.
.PP
There are other variables that are exported into preview
script environment:
.BR $w ,
.BR $h ,
.BR $x ,
.BR $y
and
.BR $id .
There are also
.B $m
and
.B $e
which store MIME type and extension of
.IR file .
.
.PP
You can specify MIME type instead of filename extension
in preview definition:
.
.IP
.EX
preview json_example application/json {{
\&    # preview json files
}}
.EE
.
.PP
You can omit subtype part of the MIME type
by replacing it with
.RB \(lq * \(rq.
.
.IP
.EX
preview any_text_example text/* {{
\&    # this one applies to all text files
}}
.EE
.
.PP
Setting subtype to
.RB \(lq * \(rq
will make the preview above apply to any file which MIME type starts with
.BR text/ .
.
.SS Setting priority
.
If there are several previews that apply to the same file type,
only the top one in the list is chosen (see
.IR "How previews are selected" ).
To alter this behavior, you can use
.B priority
command to change preview priority:
.
.IP
.EX
priority cat
.EE
.
.PP
The snippet above sets priority of a built-in preview named \(lqcat\(rq
to 1, thus now it's used for all text files.
It's possible to specify an integer as the second argument
to set priority other than 1 (may also be negative).
.
.SS Removing previews
.
.B remove
command simply removes a preview (also works for built-in ones):
.
.IP
.EX
remove cat
.EE
.
.PP
It's useful if you have a program installed on your system but you
don't want
.B ctpv
to use it for generating previews.
.
.SH FILES
.
.TP
.I $XDG_CONFIG_HOME/ctpv/config
Configuration file.
If
.I $XDG_CONFIG_HOME
is not set, defaults to
.IR \(ti/.config .
.
.TP
.I $XDG_CACHE_HOME/ctpv
Directory to store cached image previews.
It takes some time to generate an image preview for some file types,
such as videos or PDF files, this is why the generated images are
stored in the directory to be shown if the same file is previewed
again.
If
.I $XDG_CACHE_HOME
is not set, defaults to
.IR \(ti/.cache .
.
.SH SEE ALSO
.
.BR lf (1)
.
.SH AUTHOR
.
Written by Nikita Ivanov.