PATH=~/bin:/bin:/usr/bin:.
/usr/xyz/bin:~/bin2:/bin:/usr/bin:.
PATH=~/bin:~/bin2:/bin:/usr/bin:.
~/bin
~
/usr/xyz
~
~
~
argv[1] = <\a>
argv[1] = <\a>
/usr/xyz/bash
ok
~
~
make -k FOO=/usr/xyz/mumble
/usr/xyz/mumble
HOME=~
HOME=~
/usr/$x/abc
HOME=~
/usr/$x/abc
HOME=/usr/$x/abc
/usr/$x/abc