To set the PATH environment variable in the TCSH/CSH shell, you can use the following syntax:   set path = (dir1 dir2 dir3 …) Replace dir1, dir2, dir3, etc., with the directories you want to include in the PATH. For example, to add the /usr/local/bin directory to the PATH, you can use the following command: … Read more

To create a file in Unix, you can use the touch command. The touch command allows you to create an empty file with a specified name. Here’s the basic syntax:   touch file_name Replace file_name with the desired name for the new file. For example, to create a file named example.txt, you can use the … Read more

You can use the following command to list all environment variables in Linux:   printenv This will display a list of all the environment variables and their values. To view a specific environment variable, you can use the following syntax:   echo $VARIABLE_NAME Replace VARIABLE_NAME with the name of the environment variable you want to … Read more

To install Keychain on Ubuntu/Debian Linux, you can follow these steps: Update the package list:   sudo apt-get update Install Keychain:   sudo apt-get install keychain Add the following lines to your shell profile file (e.g., ~/.bashrc, ~/.bash_profile, or ~/.zshrc) to set up Keychain:   # Keychain eval “$(keychain –eval –agents ssh id_rsa)” Restart your … Read more

You can use the following commands to find out what compilers are installed or available on a Linux system: gcc -v: This will display information about the version of the GCC (GNU Compiler Collection) compiler that is installed, if any. whereis cc: This will show the location of the cc compiler, which is usually a … Read more

In Linux or Unix, you can use the sed command to print only the lines that match a specific pattern. Here’s the basic syntax:   sed -n ‘/pattern/p’ file -n – tells sed to not print any lines by default /pattern/ – specifies the pattern to match p – tells sed to print the lines … Read more

To revoke OpenSSH keys and disable user access, you need to remove the user’s public key from the authorized keys file and remove their private key from their client. Here are the steps to do this: On the server, locate the user’s authorized keys file. It’s usually located in the ~/.ssh directory. Remove the public … Read more

In Vim, you can use the :%s/old-text/new-text/g command to replace all occurrences of “old-text” with “new-text” in the entire file. Here’s a breakdown of the command: : – begins a Vim command line % – represents all lines in the file s – stands for substitute old-text – the text you want to replace new-text … Read more

To use the grep command to search for a pattern in all subdirectories of a directory in Unix or Linux, you can use the -r or –recursive option, followed by the directory path, the pattern you want to search for, and the file types you want to search in (if any). Here’s an example of … Read more

To show the progress bar with status while using the dd command in Linux, you can use the pv utility. Here’s an example of how you can pipe the output of dd to pv: dd if=/dev/sda | pv | dd of=/dev/sdb This will show a progress bar with the transfer rate, time elapsed, and estimated … Read more