simple string comparison in bash

Question

I'm looking to get the number of subdirectories within a directory and compare that with a predefined number.

Ex:

cd /Applications/
x=echo ls -d */ | wc -l | sed 's/^ *//g'
y="52"

if [ "$x" == "$y" ]; then
    echo "equal"
else
    echo "not equal"
fi

It will give me a number for x (52 in my case), but will always say "not equal". What am I doing wrong? Any help would be greatly appreciated.

Thanks

Answer 1

For bash, do this:

cd /Applications/
dirs=( */ )   # dirs is an array with the names of directories here
if (( ${#dirs[@]} == $y )); then
    echo "equal"
else
    echo "not equal"
fi

Answer 2

Replace

x=echo ls -d */ | wc -l | sed 's/^ *//g'

with:

x="$(ls -d */ | wc -l | sed 's/^ *//g')"

Explanation: When you write x=echo ls -d */ ..., bash thinks that you mean to temporarily set the the variable x to a value of "echo" and then run the ls command. You, instead, want to run the command s -d */ | wc -l | sed 's/^ *//g' and save the output in x. The construct x=$(...) tells bash to execute whatever was in the parens and assign the output to x.

Also, bash's [ command does not accept ==. Use = for string comparison. However, you really want mathematical comparison. So use '-eq':

  if [ "$x" -eq "$y" ]; then