Simple load testing script in bash

Question

Here's the code

max="$1"
date
echo "url: $2
rate: $max calls / second"
START=$(date +%s);

get () {
  curl -s -v "$1" 2>&1 | tr '\r\n' '\\n' | awk -v date="$(date +'%r')" '{print $0"\n-----", date}' >> /tmp/perf-test.log
}

while true
do
  echo $(($(date +%s) - START)) | awk '{print int($1/60)":"int($1%60)}'
  sleep 1

  for i in `seq 1 $max`
  do
    get $2 &
  done
done

This can be run as

sh load-test.sh 20 "http://api.myserver.com/get_info"

Please suggest if you think there's a way to take in multiple curl options.

Answer 1

Arithmetics in Bash

You're doing some math in Bash, some in Awk, some in a combination of both. You can do all of that in Bash alone. Most notably, instead of this:

echo $(($(date +%s) - START)) | awk '{print int($1/60)":"int($1%60)}'

This would be equivalent, but all in Bash, without additional processes:

((delta = $(date +%s) - START))
((minutes = delta / 60))
((seconds = delta % 60))
echo $minutes:$seconds

Don't use seq

seq is not portable, I suggest to avoid it. Instead of this:

 for i in `seq 1 $max`; do ...; done

You can write:

for ((i = 1; i < max; i++)); do ...; done

Don't use `...`

This syntax is obsolete today, always use $(...) instead.

Other minor things

This would be clearer as two echo lines, or a here-document with cat <<EOF:

echo "url: $2
rate: $max calls / second"

The trailing semicolon is unnecessary:

START=$(date +%s);

The quoting is unnecessary in date +'%r', but it does no harm.