Archives for January 2020

The seq command prints a sequence of integers or real numbers, suitable for piping to other programs. The seq command can come in handy in various other commands and loops to generate sequence of numbers. The Syntax The general syntax of the “seq” command is: # seq [options] specification The examples 1. To simply print […]

Question: How can we restrict user/group access to a system using ssh? SSH uses specific files for configuration to achieve these various restrictions. Inbound ssh sessions (into the host) are handled by sshd (the ssh daemon). This process has its own configuration file, /etc/ssh/sshd_config. The parameters in the /etc/ssh/sshd_config file that apply are AllowGroups, AllowUsers, […]

Question: How can we allow a user with empty password to login to a Linux system? Although it seems a risky requirement, but sometimes in a private, development environment this can come handy. Also openssh provides you with an option to have empty passwords for users while doing ssh. From the man page of sshd_config: […]

To run more that one command simultaneously we can use the & (ampersand) special character. Another use of & is running the commands in the background. In that case though, you should use & once and the end of the command or script. For example: # [some command or script] & Using & (ampersand) to […]

What is an exit code Every script, command, or binary exits with a return code. You can see this value in the special variable $?. Return codes are numeric and are limited to being between 0-255 because an unsigned 8-bit integer is used. If you use a value of -1, it will return 255. Each […]

Introduction In this article we are going to learn How to compress files using bz2 file compression tool (bzip2 linux command) and unzip bz2 compressed file. bzip2 is a open source compress tool similar to zip & gzip compression tool used to compress large sized files to reduce it’s size. bzip2 can compress files not […]