Exit Codes
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Video Transcription
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>> Hey, there Cybrarians.
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Welcome back to the Linux plus course here at Cybrary,
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I'm your instructor Rob [inaudible] ,
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and in today's lesson, we're going to
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be discussing exit codes.
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Upon completion of this lesson,
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you're going to be able to understand
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the importance of exit codes,
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as well as use the exit command to
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change the value of exit codes.
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When any command ends,
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it's going to return an exit status either
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to the shell or to the script where it was executed,
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and this status is used to determine if
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the command is completed successfully or not.
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Now the exit status value
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gets stored in a special variable.
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That variable is the
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>> dollar sign question mark variable,
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>> and we can see the contents of this variable
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>> just like we did with any other variables when we
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>> were doing variable expansion,
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we can do echo dollar sign?
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Now, when we're echoing the contents of that variable,
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if the value of the variable is the number zero,
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it means that that previous command was successful.
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But if dollar sign?
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returns any number one or greater,
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that means the previous command
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has failed and we've got an issue.
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The exit status can be changed inside of a script
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by using the exit command as well.
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This is generally done when you want to provide
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a numerical identifier for different results.
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Then once you have those
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>> different results in your code,
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>> you can perform another action upon them.
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This goes into condition statements like if
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this value was found after we ran this,
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do something else, and we're going to cover
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condition statements in a little bit.
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For now, just know that you can tell
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a command to exit and then provide a code.
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for example, we can say exit 42,
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and if we do echo dollar sign question mark.
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it will return the value 42.
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In this lesson, we covered
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the importance of exit codes as well as
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using exit commands to change exit codes.
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Thanks so much for being here and I look
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forward to seeing you in the next lesson.
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