Introduction to the built-in judgment statements of the shell in Linux

Built-in judgment, returns 0 when successful and non-zero when unsuccessful. Next, this article will focus on introducing the built-in judgment statements of the Linux shell. Friends who are interested should take a look.

Built-in judgment, returns 0 when successful, and returns non-zero if unsuccessful

Test Judgment expression

　[Judgment expression] Note that spaces must be left before and after

Numerical operations

　-eq Equal to

　- ne Not equal to

-gt Greater than

-ge Greater than or equal to

-lt Less than

-le Less than or equal to

String operation

　= Equal to

　!= Not equal to

　-z Whether it is empty

　-n Whether it is not empty

File operation

　-r Whether it exists and can be read

　-w　 Whether it exists and can be written

　-x　 Whether it exists and can be executed

　-f　Does this file exist?

　-d　Does this directory exist?

The above is the detailed content of Introduction to the built-in judgment statements of the shell in Linux. For more information, please follow other related articles on the PHP Chinese website!