The basics

No guide is going to be able to “teach you command line”. This post will attempt to point out the most useful commands for an absolute novice.

The commands

Shell navigation

ls

The ls command is probably the command that I use most frequently. It is a very simple command; it just shows the contents of the current directory (note: directory = folder). Some usage examples are below

[crayon lang=”sh”] ls #(simply list the contents of the current directory to the terminal) [/crayon] [crayon lang=”sh”] ls -l # list the contents of the current directory, one per line, full details on things like permissions, date modified, etc. This will also differentiate files from folders by adding a “d” to the front of the permission list [/crayon] [crayon lang=”sh”] ls -la # like ls -l, but also shows hidden (dot) files. [/crayon] [crayon lang=”sh”] ls .. # list the contents of the parent directory [/crayon]

pwd

The pwd command shows you what directory (folder) you are currently in. It can be helpful if you get lost in the file system.

[crayon lang=”sh”] pwd #(show your current directory)[/crayon]

Sample output:

[crayon lang=”sh”] /home/myusername/Documents/myproject/ [/crayon]

cd

The cd command is used to change directory. Together, the cd, pwd, and ls commands give you the basic tools you need to navigate the filesystem.

[crayon lang=”sh” lang=”sh”] cd .. # (change to parent directory, this will update the output of the “pwd” command to reflect that you are now one level up).[/crayon] [crayon lang=”sh”] cd myfolder/ # changes directory into the folder named “myfolder” within the current directory.[/crayon] [crayon lang=”sh”] cd OR cd \~ OR cd $HOME # takes you to your home directory[/crayon] [crayon lang=”sh”] cd / # takes you to the root of the filesystem, not often useful unless you really know what you are doing and/or have root access.[/crayon]

File Based Commands

cp

The cp command is short for “copy”. It can be used to copy a single file, or to copy a directory.

[crayon lang=”sh”] cp myfolder/myfile . # copies myfile from myfolder to the current folder[/crayon] [crayon lang=”sh”] cp -r myfolder/ backup # copies the entire contents of myfolder to backup[/crayon]

rm

The rm command is used to delete files and directories. Warning: it cannot be undone!

[crayon lang=”sh”] rm myfile.txt # deletes myfile.txt[/crayon] [crayon lang=”sh”] rm -rf myfolder # deletes myfolder[/crayon]

wget

The wget command is useful for downloading files from websites. wget is not a standard Unix command, but most linux distributions include it as it is extremely useful.

[crayon lang=”sh”] wget http://somewebsite/somefile.zip [/crayon]

cat

The cat command unfortunately has nothing to do with cats. Cat is useful for quickly showing the contents of a file to the terminal.

[crayon lang=”sh”] cat myfile.txt # spits out the contents of myfile.txt to the terminal. If myfile.txt is large, the terminal buffer may overflow.[/crayon]

Finding Files or File Contents

grep

The grep command is useful for finding text within a file. It is a little bit more advanced, but also more powerful.

[crayon lang=”sh”] grep “text i want to find” myfile.txt # searches myfile.txt for “text i want to find”. If it is found, the lines containing the match will be printed to the terminal, otherwise, nothing is printed[/crayon] [crayon lang=”sh”] grep -r “text i want to find” . # searches every file and folder rooted at the current directory for “text i want to find”. Useful if you are searching through lots of files.[/crayon]

find

The find command is useful for finding files by name, rather than searching their contents. It is also useful for quickly listing all files and folders in a directory, kind of like the ls commands, but it also works on directories inside of the current directory, and so on.

[crayon lang=”sh”] find . # shows all files and folders rooted at the current directory, including subdirectories.[/crayon] [crayon lang=”sh”] find . -name “.txt” # searches all directories for a file with the suffix “.txt”. You can use any text, but the “.” combination is useful for finding filetypes[/crayon] [crayon lang=”sh”] find . grep .txt # exactly the same as the above command[/crayon] [crayon lang=”sh”] find . -name “.txt” xargs rm # finds all .txt files in the current directory and subdirectories, and deletes them. Caution: this can be dangerous![/crayon]

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