Three Useful Terminal Commands

Three Useful Terminal Commands

See my terminal-tools tag for more articles on nifty terminal tools.

The *nix terminal is a great tool. In everyday life this is where a lot of things can be done easy and fast with this power tool. There are an abundance of tools and ways of solving problems with the terminal, but here you have three practical applications.

Find a text string within current folder

grep your_magic_string -H -R *

The command ‘grep’ is used as a search tool for plain text files matching a regular expression. In the example above we want to find the string ‘your_magic_string’ within the current folder, so we want grep to search recursively as is done through passing with the option ‘-R’ and the wildcard (‘*’). This command will return all text files within the current folder where this text streng can be found. The -H option prints the filename.

Search and replace text within a file

sed -i 's/wrong/right/g' /home/ola/list-with-stuff/somethingwrong.txt

Sed is a stream editor that parses text and implements a programming language so that this text can be modified. The script above reads a file at the endmost location (‘/home/ola/list-with-stuff/somethingwrong.txt’) and searches through the file replacing the text pattern ‘wrong’ with ‘right’. The -i option overwrite the original file with the alterations. What used to be a negative text is now super positive.

Download a file from the Internet

curl -o http:// megasecret.jpg

Curl is a nice tool to access resources on the Internet. If you want to see the source of a web-page just enter the URL after curl. For binaries and files you want to retain you can add the -o option. This lets you print the output to a file instead of displaying the text representation in your terminal window.

Bonus: Star Wars

All work and no play, makes ___________ (enter your name) a dull ___________ (enter your gender here). Bring popcorn, kick back in your chair and type the command: telnet Enjoy!


The mac terminal icon
The mac terminal icon

What many Mac OSX users doesn’t know is that the OSX is built on Unix. In the Utilities folder under Applications you will find a terminal.Through this application you can do lots of things quick and easy. A google search reveal many good tutorials

Note: If some of the commands above prompts and error message saying that the command is unknown, you would need to install the program. Use your local packet manager such as yum or apt-get to install these. On Mac macports is a nifty packet manager.

Image: The terminal can also be used for cool stuff such as surfing the waves of the internet. The picture shows the web browser Lynx. The terminal was after all the main mode of communication with the computer before the dawn of the Graphical User Interface, and is still widely used.

The Lynx Web browser displaying

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