On the commandline the elements of PATH are checked from left to right.
an example (PATH)
the command test-my-command-precedence.sh which exists in
/bin/test-my-command-precedence.sh
/usr/bin/test-my-command-precedence.sh
for the following path
~/bin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
the /usr/bin/test-my-command-precedence.sh gets precedence.