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Man Pages

Manual Reference Pages  -  LESSPIPE (1)

NAME - a filter for less


Filter Activation
Advanced Usage
Output Colorization



Usually is called as an input filter to less With the help of that filter less will display the uncompressed contents of compressed (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 supported 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_PREPROCESSOR 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 suppressed 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.


The filter is called from less provided the environment variable LESSOPEN is set properly. For the shells csh and tcsh the command

setenv LESSOPEN "| %s"

should be used, for other shells the command

LESSOPEN="| %s"; export LESSOPEN

does activate the filter for less. Use the fully qualified path, if is not in the search path. The command to set LESSOPEN can also be displayed by calling without arguments. This can even be used to set LESSOPEN directly:

eval ‘‘

Having set the environment variable as described above, less will then display textual information for a wide range of file formats.


This version of allows you to view individual files contained 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 separated chain of file names as described above.

To display files without engaging 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 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.


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). Therefore 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 colorful. 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):

Makefile .pas .patch .diff .pm .pl .pod .pov .py .rb .sh .sql ;cc .

When the conditions for syntax highlighting are met directory listings and listings of tar file contents get colorized as well.


Written by Wolfgang Friebel


Report bugs to <Wolfgang.Friebel AT>.


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.



A description of is also contained in the file README contained in the source code package

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