Compiling Erlang escript to .beam

As part of my experiments in command line Erlang escripts, I've been looking into compiling escripts into .beam files. There is a bit of a wait on starting my .escript files, and command line tools should have as little delay on startup as possible since they are generally started and stopped often.

First, I compiled my .escript files to .beam, I did this with this bash script:

erlsee.sh (get it?):

#!/usr/bin/bash
test=$1
echo $test

args=("$@")
file="$1"
echo ${file}
temp_file=$1.tmp
echo $temp_file
cp $file $temp_file
file=`echo "$1" | sed s/.escript/.erl/g` 
sed -n '1!p' $temp_file > $file
/usr/bin/env erlc $file
cp $temp_file $file
rm $temp_file

This allows you to compile an escript directly without having to remove the #! directives at the top or rename the file to have an .erl ending.

Secondly, I added the same #! headers to the .beam files, and set execution permissions (`chmod u+x *.beam`). Just open the .beam file with a text editor and paste the following lines at the top:

#!/usr/bin/env escript
%%! -smp disable


Third, I tested the running times with a very small input file with the 'time' utility. I figure this time should be dominated by the basic start up time, not the execution speeds.

$ time cat test.txt | ./runavg.escript -s 5 -i 5 | ./tgraph.escript
************************************************************************24
*********************************************15

real 0m2.077s
user 0m0.121s
sys 0m0.045s

$ time cat test.txt | ./runavg.beam -s 5 -i 5 | ./tgraph.beam
************************************************************************24
*********************************************15

real 0m2.182s
user 0m0.090s
sys 0m0.138s

I ran this multiple times, and the averages were almost equal; certainly not a big improvment. So it's not worth the extra effort to compile your escript files to .beam to improve startup times.

Execution time is another matter; it is probably improved, but that doesn't really matter for programs that just output text. They are fast enough as is.