NAME

       lessfile, lesspipe - "input preprocessor" for  less.

SYNOPSIS

       lessfile, lesspipe

DESCRIPTION

       This manual page documents briefly the lessfile, and lesspipe commands.  This manual page was written for
       the Debian GNU/Linux distribution because the input preprocessor scripts are provided by Debian GNU/Linux
       and are not part of the original program.

       lessfile  and  lesspipe  are  programs  that  can  be  used  to modify the way the contents of a file are
       displayed in less.  What this means is that less can automatically open up tar files, uncompress  gzipped
       files, and even display something reasonable for graphics files.

       lesspipe  will  toss the contents/info on STDOUT and less will read them as they come across.  This means
       that you do not have to wait for the decoding to finish before less shows you the file.  This also  means
       that you will get a 'byte N' instead of an N% as your file position.  You can seek to the end and back to
       get the N% but that means you have to wait for the pipe to finish.

       lessfile  will  toss the contents/info on a file which less will then read.  After you are done, lessfile
       will then delete the file.  This means that the process has to finish before you see it, but you get nice
       percentages (N%) up front.

USAGE

       Just put one of the following two commands in your login script (e.g.  ~/.bash_profile):

         eval "$(lessfile)"

       or

         eval "$(lesspipe)"

FILE TYPE RECOGNITION

       File types are recognized by their extensions.  This is a list of currently supported extensions (grouped
       by the programs that handle them):

         *.a
         *.arj
         *.tar.bz2
         *.bz
         *.bz2
         *.deb, *.udeb, *.ddeb
         *.doc
         *.egg
         *.gif, *.jpeg, *.jpg, *.pcd, *.png, *.tga, *.tiff, *.tif
         *.iso, *.raw, *.bin
         *.lha, *.lzh
         *.tar.lz, *.tlz
         *.lz
         *.7z
         *.pdf
         *.rar, *.r[0-9][0-9]
         *.rpm
         *.tar.gz, *.tgz, *.tar.z, *.tar.dz
         *.gz, *.z, *.dz
         *.tar
         *.tar.xz, *.xz
         *.whl
         *.jar, *.war, *.xpi, *.zip
         *.zoo
         *.tar.zst, *.tzst
         *.zst

USER DEFINED FILTERS

       It is possible to extend and overwrite the default lesspipe and lessfile  input  processor  if  you  have
       specialized  requirements.  Create  an  executable program with the name .lessfilter and put it into your
       home directory. This can be a shell script or a binary program.

       It is important that this program returns the correct exit code: return 0  if  your  filter  handles  the
       input, return 1 if the standard lesspipe/lessfile filter should handle the input.

       Here is an example script:

         #!/bin/sh

         case "$1" in
             *.extension)
                 extension-handler "$1"
                 ;;
             *)
                 # We don't handle this format.
                 exit 1
         esac

         # No further processing by lesspipe necessary
         exit 0

FILES

       ~/.lessfilter
              Executable  file  that  can  do user defined processing. See section USER DEFINED FILTERS for more
              information.

BUGS

       Sometimes, less does not display the contents file you want to view but output that is produced  by  your
       login  scripts  (~/.bashrc  or ~/.bash_profile). This happens because less uses your current shell to run
       the lesspipe filter. Bash first looks for the variable $BASH_ENV in the environment expands its value and
       uses the expanded value as the name of a file to read and execute. If this file produces any output  less
       will  display  this.  A  way to solve this problem is to put the following lines on the top of your login
       script that produces output:

         if [ -z "$PS1" ]; then
             exit
         fi

       This tests whether the prompt variable $PS1 is set and if it isn't (which is the case for non-interactive
       shells) it will exit the script.

SEE ALSO

       less(1)

AUTHOR

       This manual page was written by Thomas Schoepf <schoepf@debian.org>, for the Debian GNU/Linux system (but
       may be used by others). Most of the text  was  copied  from  a  description  written  by  Darren  Stalder
       <torin@daft.com>.

                                                                                                     LESSOPEN(1)