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

The “PHP Warning: fread(): Length parameter must be greater than 0” error message is typically thrown when the fread() function in PHP is passed an argument of zero or a negative number as the length of data to be read from a file. The fread() function expects a positive integer as the length parameter, and … Read more

To securely delete all files in Linux AWS, you can use the shred command. Shred overwrites the file contents multiple times, making it difficult to recover the data. To delete all files in a directory, you can use the following command: find /path/to/directory -type f -exec shred -uvz {} + This command finds all files … Read more

To add a static route in Ubuntu Linux, you need to edit the /etc/network/interfaces file and add a line to define the static route. For example, to add a static route for the network 192.168.1.0/24 via the gateway 192.168.2.1, you would add the following line to the /etc/network/interfaces file: up route add -net 192.168.1.0/24 gw … Read more

To find and delete all empty directories and files in Linux or Unix, you can use the find command with the -empty option. For example, to delete all empty files and directories in the current directory: find . -empty -delete Or, to delete all empty directories in the current directory: find . -type d -empty … Read more

To use grep to include only *.txt file patterns when running in recursive mode, you can use the -r option to specify recursive search and the –include option to specify the file pattern to include. For example: grep -r ‘pattern’ –include=’*.txt’ /path/to/directory This will search for the string pattern in all *.txt files under the … Read more

To check the swap usage size and utilization in Linux, you can use the free command with the -h option to display the output in human-readable format. free -h The output will show the total amount of swap memory, used swap memory, and free swap memory, as well as other information about the system’s memory … Read more