less command and syntax highlighting

Question

I need to use the less command with the syntax highlighting of the vim command for python, C, bash and other languages.

How do I apply syntax highlighting colors according to vim colors for less command?

Solution 1

Syntax highlighting of less, works just fine on most *nix systems.

apt install source-highlight
export LESSOPEN="| /usr/share/source-highlight/src-hilite-lesspipe.sh %s"
export LESS=' -R '

On Fedora/RedHat based distros use /usr/bin/src-hilite-lesspipe.sh instead.

Even on Cygwin you can do it with the minor adjustment of the shell script path and installing with apt-cyg instead of apt.

However, using this drastically slows down browsing of large files. I suggest to use alias in such a way to only implement the LESSOPEN export above when needed, like this:

alias lessh='LESSOPEN="| /usr/bin/src-hilite-lesspipe.sh %s" less -M '

where the -M flag is convenient to also show filename and line number.

Also remember to copy the script into your bin path:

cp /usr/share/source-highlight/src-hilite-lesspipe.sh /usr/bin/src-hilite-lesspipe.sh

---

UPDATE: 2019-07-24

Apparently, on more recent Cygwin installs, you have the following files in your path:

source-highlight.exe
source-highlight-esc.sh
source-highlight-settings.exe

So now you also need to execute the source-highlight-settings.exe that will add the configuration file:
$HOME/.source-highlight/source-highlight.conf.

Solution 2

less doesn't support syntax highlighting.

vim, like all vi clones has a read-only mode called view which you can use to just view files. it supports all features of vim including syntax highlighting.

e.g.

view filename.py

the main difference between view and vi is that view doesn't "lock" the file you're viewing by creating a .swp file.

Solution 3

I tend to disagree with Ingo, less can be taught to highlight syntax. Check out this answer on SuperUser. Basically, you have to install GNU's source-highlight (available in all major distro package repos), and then add the following to your .bashrc (or .bash_profile or what have you):

export LESSOPEN="| /path/to/src-hilite-lesspipe.sh %s"
export LESS=" -R "

However, note that source-highlight is not as powerful as vim's highlighter. Use whatever suits you best.

Solution 4

less cannot be taught to highlight syntax elements, but Vim can be used as a pager, i.e. a replacement for less. There are more advanced plugins, but the basic script actually ships with Vim ($VIMRUNTIME/macros/less.sh). For the full information, see Using vim as a syntax-highlighting pager on the Vim Tips Wiki.

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Comments

[PersianGulf]

if your view command means from radare package , it's not read only

[Felix]

Hmm, my view command doesn't seem to support syntax highlighting. I've tried :syntax enable and :syntax on, but I always get syntax: Not an editor command. My vim supports highlighting, though.

[Alessio]

@felix - do you have another vi like nvi or elvis installed? check your /usr/bin/view - on my debian system, it's a symlink to /etc/alternatives/view which is, in turn, a symlink to /usr/bin/vim.basic.

[Felix]

Hmm, in my case it's a symlink to /usr/bin/ex, which, curiously, is owned by the vi package.

[Alessio]

ah, but which vi package? vim? elvis? nvi?

[not2qubit]

I'm surprised people doesn't even bother to Google before posting wrong answers...

[Ingo Karkat]

@user1147688: If you carefully read Felix's answer, the GNU source-highlight is an external program, and the integration with less is very loose. It's not less that does the highlighting; but Vim indeed has this capability built-in.

[SMBiggs]

The alias 'lessh' doesn't work for me. Running bash on osx. Sigh.

[not2qubit]

That is an entirely different issue, most likely due to OSX using different shell and environment options, which may affect the interpretation of single and double quotes, differently. You can check and set these with shopt -p and set.

[x-yuri]

I can confirm what @Felix says, on arch linux view is a symlink to /usr/bin/ex of core/vi package.

[x-yuri]

See this answer: alias vless='vim -u $VIMRUNTIME/macros/less.vim'

[michael]

+1 but I'm sure what these comments are trying to say -- can't tell if they're even positive or negative ("...google before posting wrong answers"?, "installing xyz is more correct than just using vim"?). This answer is clearly the "most correct answer". Basically the OP didn't know this feature of vim existed, and this answer lets the OP know that it exists. Occam's razor ftw. The answer could only be improved by showing an example, e.g., $ diff file1.c file2.c | /usr/share/vim/vim74/macros/less.sh

[mhvelplund]

This worked for me on OSX: first I installed with: brew install source-highlight, then I added an alias: alias lessh='LESSOPEN="| src-hilite-lesspipe.sh %s" less -R '

[Michael]

To use highlighting in a pipe, like grep something somewhere | less use this on vi: grep something somewhere | view -

[Usman Khan]

Erm, less does support syntax highlighting on 3 out of 3 of my systems...