# lessfile(1) - man - phpMan [LESSOPEN(1)](https://www.chedong.com/phpMan.php/man/LESSOPEN/1/markdown) General Commands Manual [LESSOPEN(1)](https://www.chedong.com/phpMan.php/man/LESSOPEN/1/markdown) ## 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 pro‐ vided 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, un‐ compress 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 exten‐ sions (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 han‐ dles 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 pro‐ duced 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)](https://www.chedong.com/phpMan.php/man/less/1/markdown) ## AUTHOR This manual page was written by Thomas Schoepf <>, 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 <>. [LESSOPEN(1)](https://www.chedong.com/phpMan.php/man/LESSOPEN/1/markdown)