Basic Commands: Difference between revisions

To display all available signals:

To kill the PID 257:

Use the ping, also known as the Packet Internet Groper, command to check network connectivity between two computers. You can use this command to troubleshoot connectivity, name resolution, and reachability. It accepts an IP address or an URL as an input.

To check network connectivity to 172.168.1.1 IP address and send 5 data packets:

Use the vi and nano commands to create a new file, read a file, or edit an existing file. Vi is the default text editor for several Linux distributions and it is very simple to use. Nano is a terminal-based text editor that is ideal for making some changes to any files or creating basic plain text files.

To open the existing file or to create a new file:

or

Use the history command to view the history of all the previously executed terminal commands that you run. The maximum number of entries that BASH should store can be defined in your .bashrc file. Linux commands that you execute are considered events and every event is associated with an event number. You can recall, remove, or change commands using their event numbers.

To list the last 5 commands, including itself:

To remove the history of event number 1525:

Note: history command behavior may change depending on the shell you are being used.

Use the passwd command to change the user account password. A normal user can change only their own password, but the root user or user with sudo privileges can change the password of any user account. This command can also be used to delete or expire an account password.

To change the password for the user bob:

Use the which command to locate the executable file of the specified command. This command searches for the executable file location in the $PATH environment variable. The which command returns any of the following status:

To display executable file locations for useradd command, type:

Use the less command to view the contents of a file one screen at a time, starting at the beginning. This command provides the capability of both backward and forward navigation. The less command has quick file access because it does not access the entire file if the file is large.

To display the contents of the updates.txt file one screen at a time.

Use the tail command to view the contents of a file, starting at the bottom. By default, it displays the last 10 lines of the file, but you can change this default behavior. The tail command can also be used to monitor the file. When you add new lines to the file, then the display is updated.

To display the last 10 lines of the file updates.txt:

To display the last 15 lines of the file access.log:

Use the head command to display the contents of a file, starting at the beginning. By default, it displays the first 10 lines of the file, but you can change this default behavior.

To display the first 10 lines of the file updates.txt:

Use the grep, also known as global regular expression print, the command to search for a word or string of characters in a file or directory. The search pattern is termed regular expression. When the grep command finds a matching string in the file, then this command prints the line that contains the string.

To search for the string 'welcome' in the file log.txt:

Use the diff command to do a line-by-line comparison of two files and display their differences. You can also use this command to compare the contents of Linux directories.

To show differences between two files named source.java and newsource.java, type

To show differences between Documents and Docs directories.

Use the find command to search and locate the files and directories that match the specified conditions. This command enables you to search using file or folder name, creation date, modification date, permissions, and owner.

To search the file named program.py in the /home/linuxopsys/projects directory, type:

To search for files with given permissions in the current directory:

Use the echo command to display the specified text or string on the terminal. This command is most commonly used in batch files and scripting languages to display standard text output. You can also use this command to display the values of an environment variable.

To print the string “This is a sample string” on the terminal:

This is a sample string

To print the value of the PATH environment variable:

Output:

Use the shutdown command to gracefully and securely shut down your Linux computer.

To restart your system after 5 minutes:

To immediately restart your computer:

The Alias command allows you to define temporary aliases for current sessions. It allows you to execute one or more commands.

Create a new alias named 'lsall', type:

Lists all aliases for the current session:

Note: Alias behavior may change depending on the shell you are being used. It is traditionally used in bash shell.

The exit command ends a shell session and closes the terminal you are using

The wget command is used to retrieve or download content from the internet.

To download WordPress using wget, type:

The latest.tar.gz file will be downloaded to the current directory.

The clear command is used in Linux to clear the terminal screen. This is similar to cls command in other operating systems.

==Source==

*[https://linuxopsys.com/topics/basic-linux-commands linuxopsys.com]