If you’re a developer, you probably find yourself using Linux at least some of the time. Knowing your way around the OS can make your life a lot easier, and I’ve sometimes found myself wishing I knew certain commands or concepts a lot sooner. I’m no expert, but since I thought it might be useful, I’ve put together a short quiz to test your Linux skills.
So, let’s get started…
- What does the cd command do when handed each of the following inputs: “-“, “/tmp” and “~”? [+]
- “cd -” changes the current directory to the directory you were previously in.
- “cd /tmp” changes the current directory to “/tmp”
- “cd ~” changes the current directory to your home directory.
- What are two ways of copying a text file without using the cp command? [+]
- cat the file and redirect the output to a new file.
- Use the scp command (secure copy).
- You want your console window to continuously show you the latest updates to a log file as its being updated. How would you do this? [+]
- Use the tail command with the -f flag.
- Use the less command with the +F option (personal favorite).
- What is the difference between the “which” and “whereis” commands? [+]
- which shows the full path of a given command.
- whereis locates source, binary, and manual files for a given command.
- How would you find all of the files modified within the last day under a particular directory structure? [+]
- find ./ -type f -mtime -1
- What is the purpose of the “/etc” and “/var” directories? [+]
- The main directory layout for all Linux systems is based on the Filesystem Hierarchy Standard (FHS).
- The “/etc” directory contains host-specific, system-wide configuration files (sometimes called “Editable Text Configuration”).
- The “/var” directory contains “variable files”, or files whose content is expected to continuously change during the normal operation of the system (ex: log files).
- What are “cron jobs”? [+]
- Linux systems have a program called “cron” which runs in the background and executes jobs (commands, scripts, etc) based on a schedule defined in a crontab file. This allows you to routinely do certain tasks. A “cron job” refers to a job run by the cron daemon.
- What does the “nohup” command do? [+]
- Short for No Hang Up, this command allow you to execute a command that will keep going after you’ve logged out (ie, one that ignores hang up signals).
- You have a directory tree which contains all of the files for a web application. You want to make a list of all of the files that contain a phone number in the format of “(XXX) XXX-XXXX”. How would you do this? [+]
- The key insight is to use the grep command with the -R flag (recursive directory search), -l flag (list files) and a regular expression to find the phone numbers.
- As a side note, this used to be a popular interview question that Amazon gave to potential applicants (for more info, see the “Notes” section at the bottom of this post).
- What is the name of the official Linux kernel mascot? [+]
Mouse over or click the +’s to see possible answers (though I didn’t include all possible answers – so you may have thought of some solutions that aren’t listed).
If you found yourself doing poorly, or just want to refresh your linux skill set, check out:
They have some of the best tutorials I’ve seen on Linux. However, if anyone knows of any other good tutorials let me know and I’ll add them here too.
- For more information on question 9, click here and go to the section titled “Area Number Three: Scripting and Regular Expressions”.