Running scripts from other directory

a.sh

echo "a.sh is run"
pwd

echo ""
echo "First B"
# Doesn't work if in a different directory
source b.sh

echo ""
echo "Second B"
# DOES work from different directory
source $(dirname "$0")/b.sh

b.sh

echo "b.sh is run"
pwd
echo "Script location: $0"

example.log

user:~$ echo $HOME
/Users/user
user:~$ ls
test/
user:~$ cd test
user:~/test$ ./a.sh 
a.sh is run
/Users/user/test

First B
b.sh is run
/Users/user/test
Script location: ./a.sh

Second B
b.sh is run
/Users/user/test
Script location: ./a.sh
user:~/test$ cd ~
user:~$ test/a.sh 
a.sh is run
/Users/user

First B
test/a.sh: line 7: b.sh: No such file or directory

Second B
b.sh is run
/Users/user
Script location: test/a.sh