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Linux Shell Scripting Essentials by Sinny Kumari

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Testing expressions with a test

The shell builtin command test can be used to check file types and compare expressions value. The syntax is test EXPRESSION or the test command is also equivalent to [ EXPRESSION ].

It returns the exit code 1 (false) if the EXPRESSION result is 0, and 0 (true) for a non-zero EXPRESSION result.

If no EXPRESSION is provided, the exit status is set to 1 (false).

File checks

Different kinds of checks can be done on the file using the test command; for example, file existence test, directory test, regular file check, symbolic link check, and so on.

The options available to do various checks on a file are explained in the following table:

Option

Description

-e

fileChecks whether the file exists

-f file

The file is a regular ...

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