In shell scripting you sometimes come across comparisons where each value is prefixed with "x". Here are some examples from GitHub: if [ "x${JAVA}" = "x" ]; then if [ "x${server_ip}" = "xlocalhost" ]; then if test x$1 = 'x--help' ; then I’ll call this the x-hack. For any POSIX compliant shell, the value of the x-hack is exactly zero: this comparison works without the x 100% of the time. But why wa