These commands are from RedHat. So, it might change based on Unix Flavor.
- To check the Unix Flavor running on the machine use “uname -a” or “cat /proc/version“
- To check how many users are configured in local machine
- Check the name list in /home directory. Use “ll” or “ls –l”
- Check the /etc/passwd file. “cat /etc/passwd”
- Each entry in the /passwd file would be “login-name:password (shown as ‘x’ in to hide/shadow):user ID:group ID:user detail:home directory:shell
- Actual password would be in “/etc/shadow” file in encrypted form. Only root can access.
- The groups which a user belongs to will be in “/etc/groups” file.
- We can see the available shell prompts in “cat /etc/shells” command
- Users can be added via “useradd <name>” and “passwd <name>” command.
- “chmod” to modify the mode of a file.
- First letter will say whether it is directory or single file. d or –
- First ‘rwx’ shows the read,write,execute permission for the user who created that file.
- Second ‘rwx’ shows the above permission for users of same group
- Third ‘rwx’ shows the permission for all other users.
- “Chmod 750 file-name” will make the mode of that file as 111-101-000
- We can install application using “apt-get” or “yum” command. [Provided yum is installed]