Shell string Equality Comparison, note the processing when the string is empty

if ["$test" x = "Test" x]

Here are a few key points:
1 with a single equals sign, two equals signs can be
2 Note that there is a space on each side of the equal sign: This is the UNIX shell requirement
3 Notice the last X of "$test" X, which is deliberately arranged, because when $test is empty, the expression above becomes x = Testx, which is obviously not equal.

Without this x, the expression would be an error: [: =: unary operator expected

This article is from the Linux and networking blogs, so be sure to keep this source http://khaozi.blog.51cto.com/952782/1768437

Shell string Equality Comparison, note the processing when the string is empty