These exercises will help you master regular expressions.
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Display a list of all the users on your system who log in with the Bash shell as a default.
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From the /etc/group directory, display all lines starting with the string "daemon".
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Print all the lines from the same file that don't contain the string.
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Display localhost information from the /etc/hosts file, display the line number(s) matching the search string and count the number of occurrences of the string.
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Display a list of /usr/share/doc subdirectories containing information about shells.
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How many README files do these subdirectories contain? Don't count anything in the form of "README.a_string".
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Make a list of files in your home directory that were changed less that 10 hours ago, using grep, but leave out directories.
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Put these commands in a shell script that will generate comprehensible output.
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Can you find an alternative for wc -l, using grep?
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Using the file system table (/etc/fstab for instance), list local disk devices.
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Make a script that checks whether a user exists in /etc/passwd. For now, you can specify the user name in the script, you don't have to work with arguments and conditionals at this stage.
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Display configuration files in /etc that contain numbers in their names.