How to check dependency in bash script

Question

I want to check whether nodejs is installed on the system or not. I am getting this error:

Error : command not found.

How can i fix it?

#!/bin/bash

if [ nodejs -v ]; then
echo "nodejs found"
else
echo "nodejs not found"
fi

Answer 1

You can use the command bash builtin:

if command -v nodejs >/dev/null 2>&1 ; then
    echo "nodejs found"
    echo "version: $(nodejs -v)"
else
    echo "nodejs not found"
fi

Answer 2

The name of the command is node, not nodejs

which returns the path to the command to stdout, if it exists

if [ $(which node 2>/dev/null) ]; then
  echo "nodejs found"
else
  echo "nodejs not found"
fi