lesspipe man page on DragonFly
[printable version]
LESSPIPE.SH(1) User Commands LESSPIPE.SH(1)
NAME
lesspipe.sh - a filter for less
SYNOPSIS
lesspipe.sh [FILE[s]]...
DESCRIPTION
Usually lesspipe.sh is called as an input filter to less With the help
of that filter less will display the uncompressed contents of com‐
pressed (gzip, bzip2, compress, rar, 7-zip, lzip, xz or lzma) files.
For files containing archives and directories, a table of contents will
be displayed (e.g tar, ar, rar, jar, rpm and deb formats). Other sup‐
ported formats include nroff, pdf, ps, dvi, shared library, MS word,
OASIS (e.g. Openoffice), NetCDF, html, mp3, jpg, png, iso images,
MacOSX bom, plist and archive formats, perl storable data and gpg
encrypted files. This does require additional helper programs being
installed.
If at configure time support for the ENV variable LESS_ADVANCED_PRE‐
PROCESSOR was included then files with mostly ASCII text such as html,
ps, rtf and files with alternate character encoding remain normally
unprocessed (see below)
The filter does not only display the above mentioned file formats, but
can also be applied recursively up to a depth of 6 where applying a
decompression algorithm counts as a separate level.
In a few rare cases the file command does not recognize the correct
format (especially with nroff). In such cases filtering can be sup‐
pressed by a trailing colon on the file name.
If the file command reports text with UTF-8, ISO-8859-1 or UTF-16
encoded characters then the text will be transformed using iconv into
the default encoding. This does assume iconv has the right default
which can be wrong in some situations.
To suppress informal messages in the first line of the filter output
the ENV variable LESSQUIET can be set to a nonempty value.
FILTER ACTIVATION
The filter is called from less provided the environment variable
LESSOPEN is set properly. For the shells csh and tcsh the command
setenv LESSOPEN "|lesspipe.sh %s"
should be used, for other shells the command
LESSOPEN="|lesspipe.sh %s"; export LESSOPEN
does activate the filter for less. Use the fully qualified path, if
lesspipe.sh is not in the search path. The command to set LESSOPEN can
also be displayed by calling lesspipe.sh without arguments. This can
even be used to set LESSOPEN directly:
eval `lesspipe.sh`
Having set the environment variable as described above, less will then
display textual information for a wide range of file formats.
ADVANCED USAGE
This version of lesspipe.sh allows you to view individual files con‐
tained in a file archive, which itself may even be contained in another
archive.
The notation for viewing files in multifile archives is
less archive_file:contained_file
or even
less super_archive:archive_file:contained_file
To display a file in raw format, a colon (:) has to be appended to the
file name. To suppress the decompression of files two colons have to
be appended. This does apply as well to the last file in the colon sep‐
arated chain of file names as described above.
To display files without engaging lesspipe.sh temporarily, the command
cat filename | less
can be used instead of unsetting the environment variable LESSOPEN
If the ENV variable LESS_ADVANCED_PREPROCESSOR is respected by
lesspipe.sh then files containing mostly ASCII text get displayed
unmodified. To activate filtering for such formats the contents of
LESS_ADVANCED_PREPROCESSOR has to be set to an non empty value.
OUTPUT COLORIZATION
The filter is able to do syntax highlighting for the languages ada,
asm, awk, c, c++, groff, html, xml, java, javascript, lisp, m4, make,
pascal, patch, perl, povray, python, ruby shellscript and sql by using
code2color as the colorizing program. A different colorizer can be
called within code2color by setting the ENV variable LESSCOLORIZER to
the name of an alternative (currently only pygmentize allowed). There‐
fore code2color is always needed for syntax highlighting.
ATTENTION: Syntax highlighting is only activated, if the environment
variable LESS exists and contains the option -R or -r or less is called
with one of these options. This guarantees, that instead of literal
escape sequences, colors are displayed. The detection of the -r/-R
presence at runtime is rather dependent on the operating system and may
not work in all cases. Putting the option in the LESS environment
variable is guaranteed to work.
As syntax highlighting is rather resource intense, it can be switched
off by appending a colon after the file name, if the output was color‐
ful. If the wrong language was chosen for syntax highlighting, then
another one can be forced by appending a colon and a suffix to the file
name.
The following suffixes are recognized (works with code2color only):
.ada .asm .inc .awk .c .h .cpp .cxx .groff .html .php .xml .java .js
.lsp .m4 Makefile .pas .patch .diff .pm .pl .pod .pov .py .rb .sh .sql
When the conditions for syntax highlighting are met directory listings
and listings of tar file contents get colorized as well.
AUTHOR
Written by Wolfgang Friebel
REPORTING BUGS
Report bugs to <Wolfgang.Friebel AT desy.de>.
COPYRIGHT
Copyright © 2005-2015 Wolfgang Friebel
This is free software; see the source for copying conditions. There is
NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.
SEE ALSO
less(1)
A description of lesspipe.sh is also contained in the file README con‐
tained in the source code package
lesspipe.sh Oct 2011 LESSPIPE.SH(1)
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