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

巴扎黑
巴扎黑Original
2017-08-12 16:40:321544browse

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?

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