Basic linux commands
Linux

Basic Linux Commands Made Easy Part2

In the previous post, we discussed some Linux commands and we saw how to show files, traverse directories, make them, and much more. Now, that was just the first level of the basic Linux commands. Let’s take one more step and see more of the basic Linux commands that you will use.

 

We talked about the ls command in the previous post and we’ve discussed only 2 parameters. Let’s dig deeper and see more parameters that can make you more powerful.

ls -R  to recursively list all files in a directory

The -R parameter will traverse deeply till it finishes all directories. As you can see, for large directory structures, this can become quite a large output listing.

ls -R command

ls r  Reverses the sorting order for the displayed files and directories.

ls -r- command

ls -S  Sorts the output by file size.

ls -lS command

ls -t  Sorts the output by file modification time.

ls -lt command

Filtering Output

ls -l myfile?

A question mark is used to represent one character.

ls -l myprob*

An asterisk is used to represent zero or more characters.

The question mark and asterisk are called wild characters.

ls wild character

Creating Files

touch test1

The touch command is used to create an empty file. You can use the touch command to change the access and modification times of an existing file without changing the file contents.

touch command

If you use it against an existing file, it will change the access time, if the file doesn’t exist, it will create it.

In order to change the modification time,  just type it with -t followed by the time with the following format YYYYMMDDHHMM

touch -t 202012011200 test1

touch existed file

Linking files

We know from the previous post that cp command is used to copy files.

What about creating a shortcut to that file in a different place. In Linux, this is called linking files.

There are two different types of file links in Linux:

  • hard link
  • symbolic, or soft link

cp -l file1 file2

Hard Links

The hard link creates a separate file which contains information about the original file and where it is located.

Keep in mind that you can only create a hard link between files on the same physical drive, you can’t create hard links between files under separate mount points.

If you need to create links on a different physical drive, you’ll have to create a soft link instead.

cp hardlink

Symbolic Links

The -s parameter creates a symbolic or soft link:

cp -s file1 file2

cp softlink

Here we should mention also another command that makes links other than cp which is ln command, you can create hard and soft links with it like this:

ln myfile myfile2

This command creates a hard link.

ln command

ln -s myfile myfile2

This command creates a soft link.

ln softlink

Viewing the file type

file myfile

Determines the kind of the file.

file command

Viewing parts of a file

We know also from the previous post the cat command and the less command. Another important command that you will use a lot in your daily work which is the tail command.

The tail command

This command displays the last 10 lines of a file.

-n parameter to specify the number of lines

-f parameter to stay on the file and continue to watch the last lines you specified like monitoring, and this is very important when looking at log files.

tail command

The head command

Like tail command, but this command displays the first 10 rows of a file with the same tail command parameters.

head command

Running Processes

ps aux

This command is to see the currently running processes.

ps aux

top command shows the running processes.

-c parameter to show the command path that is running.

top command

kill command to kill a running process.

To kill a process

pkill processName

kill command

type xkill and press Enter to kill any nonresponsive window.

xkill command

 

df command shows the disk free space.

df -h

-h for human readable value

df command

That was some of the basic Linux Commands. I hope you enjoy it. Keep coming back.