Learn Linux Shell Scripting - Fundamentals of Bash 4.4

Test shorthand

The test command is one of the most important commands we have in our shell scripting arsenal. Because shell scripts can often be fragile, especially where user input is concerned, we want to make these as robust as possible. While explaining every aspect of the test command would take a whole chapter, the following are the things test can do:

• Check whether a file exists
• Check whether a directory exists
• Check whether a variable is not empty
• Check whether two variables have the same values
• Check whether FILE1 is older than FILE2
• Check whether INTEGER1 is greater than INTEGER2

And so on and on and on—this should give you at least an impression of things you can check with test. In the Further reading section, we have included ...