Dammit Jim!

I was just quickly flipping through code on a terminal and got to thinking that it would be pretty handy to be able to syntax highlight when using head or grep without having to open an editor. Luckily, I remembered Pygmentize was pretty handy when syntax highlighting in LaTeX so I wondered if they had an equivalent output for terminal. It turns out they do (in standard or 256 color no less) so in a couple minutes I had a really short script for highlighting code at the terminal saved it to bin/ccat and was ready to go. Pygmentize really is impressive. Here’s the script if anyone else is looking to do the same: [bash] #!/bin/bash if [ ! -t 0 ];then file=/dev/stdin elif [ -f $1 ];then file=$1 else echo “Usage: $0 code.c” echo “or e.g. head code.c|$0” exit 1 fi pygmentize -f terminal -g $file [/bash] It just looks for stdin and if it doesn’t find it it looks for a file name or takes direct input. Obviously it requires Pygmentize (which is really easy to install if you already have Python).

gioby of Bioinfo Blog! (an interesting read by the way) left a comment asking about displaying code in LaTeX documents. I’ve sort of been cludging around using \hspace‘s and \textcolor but I’ve always meant to figure out the right way to do things so this seemed like a good chance to figure out how to do it right.

LaTeX tends to ignore white space. This is good when you’re writing papers but not so good when you’re trying to show code where white space is an essential part (e.g. Python). Luckily there’s a builtin verbatim environment in LaTeX that is equivalent to html’s <pre>. So something like the following should preserve white space.

\begin{verbatim}
for i in range(1, 5):
  print i
else:
  print "The for loop is over"
\end{verbatim}

Unfortunately, you can’t use any normal LaTeX commands inside verbatim (since they’re displayed verbatim). But luckily there a handy package called fancyvrb that fixes this (the color package is also useful for adding colors). For example, if you wanted to highlight “for” in the above code, you can use the Verbatim (note the capital V) environment from fancyvrb:

\newcommand\codeHighlight[1]{\textcolor[rgb]{1,0,0}{\textbf{#1}}}
\begin{Verbatim}[commandchars=\\\{\}]
\codeHighlight{for} i in range(1, 5):
  print i
else:
  print "The for loop is over"
\end{Verbatim}

If you really want to get fancy, the Pygments package in Python will output syntax highlighted latex code with a command like: pygmentize -f latex -O full test.py >py.tex The LaTeX it outputs is a bit hard to read but it’s not too bad (it helped me figure out the fancyvrb package) and it does make nice syntax highlighted output.

Here’s an example LaTeX file with the three examples above and the pdf it generates if you’re curious.

• codeInLatex.tex
• codeInLatex.pdf