We are finally ready to see what makes the shell such a powerful programming environment. We are going to take the commands we repeat frequently and save them in files so that we can re-run all those operations again later by typing a single command. For historical reasons, a bunch of commands saved in a file is usually called a shell script, but make no mistake: these are actually small programs.
Then we save the file ( Once we have saved the file, we need to change the file permission to execute. This is done using chmod as: Now, we run the following command:
Let’s start by going back to
The command
This is a variation on the pipe we constructed earlier: it selects lines 11-15 of the file
Then we save the file ( Once we have saved the file, we need to change the file permission to execute. This is done using chmod as: Now, we can ask the shell to execute the commands it contains. so we run the following command:
Sure enough, our script’s output is exactly what we would get if we ran that pipeline directly.
In the above script, we have selected 11-15 line from the octane.pdb. What if we want to select lines from an arbitrary file? We could edit Now, within “nano”, replace the text
Inside a shell script,
We can now run our script like this:
or on a different file like this:
We still need to edit
We can now run:
By changing the arguments to our command we can change our script’s behaviour:
This works, but it may take the next person who reads
A comment starts with a What if we want to process many files in a single pipeline? For example, if we want to sort our because
Which of the following is a basic variable type designed to store whole numbers?The integer data type ( int ) is used to represent whole numbers that can be stored within 32-bits.
Which of the following OSS uses a Web browser as its main user interface?Chrome OS uses a Web browser as its main user interface. An operating system cross-platform compatibility feature allows certain types of data files created on one type of OS to be seamlessly read and modified on a different OS type.
Which of the following steps enable displaying protected system files in Windows 8 8.1 10?Select the View tab. Click the drop down for Options and select "Change folder and search options" Select the View tab. From the Advanced settings menu, mark the "Show hidden files, folders, or drives" and uncheck "Hide protected operating system files (Recommended)"
Which of the following actions would be of help while troubleshooting a black blank screen on a Windows based PC?Which of the following actions would be of help while troubleshooting a black/blank screen on a Windows-based PC? Unplug and restart the printer. Check cables or wireless connection. Uninstall and reinstall the printer.
|