Useful Linux Commands

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#LINUX

#DEVOPS

Useful Linux Commands

Linux is very popular open source operating system, just like mac and windows you can use a graphical interface with it, but to truly harness the power of linux its recommended to use its shell (command line interface). In windows its cmd and in mac its the terminal

Before i continue i want to go over what a command really is. Since Linux is vastly customizable, there are a lot of different variations of linux that share the core programs but also come with its own programs and user interface and look and feel. These variations are whats called distros (distributions), some popular distros are Ubuntu, Arch Linux, Linux Mint. A command is a way to run a program that runs on that distros using the shell (command line interface). A command consist of that programs name along with any options and/or arguments.

Now a lot of us already use basics file system commands in our day to day already like ls (list files), mkdir (make directory) but these are some other ones i find useful.

diff command is used to compare two files or directories. when comparing files it compares them line by line and when comparing directories it compares the files in those directories.

diff [options] file1 file2 ↑ this will compare two files line by line print out its differences diff [options] directory1 directory2 ↑ this will compare two directories and list its differences

grep this command is very powerful it can take a text or regular expression called pattern and iterate over a file(s) and list any line where it finds that pattern.

grep [options] pattern [files] ↑ this will iterate over all the files and list the lines where it finds those patterns in the files.

cat you ever want to read the contents of a file right inside your command line interface? well the cat command does just that, it prints the entirety of the file. It concatenates the file into one stdout (standard output).

cat file ↑ this will list the whole file content inside the terminal

convert, often times i would need to convert an image type from one format to another or even compress the image, prior to to knowing about this command i would use some sort of online converter, but we can easily use the convert command. Keep in mind that the convert command does not come built in with most distributions, It is part of the package called ImageMagick

convert [input-options] input-file [output-options] output-file convert me.jpeg me.jpg ↑ this will take an input file of a type and create a new file of another type convert me.jpeg -quality 50% me.jpg ↑ this will take an input file of a type and create a new compressed file of another type

aspell, since i can not spell this is the perfect command for me, it runs a spell checker for any file with suggestions. This package does not come pre installed with OS so we need to install it with homebrew

brew install aspell aspell -c file ↑ this will check the file and give suggestions on words it does not recognize

This is a great alternative to when KeithBot is not around to help correct my spelling mistakes