UNIX/Linux/Ubuntu system administration DAY 02

Linux system commands

1. lastb : show details of failed logins
2. last : display the last login and logout details of all users
3. uptime: display how long the system has been running
4. who: list of users who are currently logged in to the system
5. w: display information about users currently logged in to the system
6. telinit: change run levels (e.g. single user mode: run level 1)
7. netstat -rn: check the default gateway on an unix/linux machine

Useful Linux commands

1. apropos: search for strings that exist in each Linux command e.g. apropos printing
2. cat /etc/shells: list all available shells in the system
3. set: display all environmental settings

Managing users and groups

1. /etc/passwd
2. /etc/groups: consists of a list of groups each in a different line

Managing partitions

1. fdisk: mange partition table
2. sfdisk: manage partition table
3. parted: a partition manipulation program
4. partprobe: inform the OS of partition table changes

Manage packages using RPM

1. rpm -i packagename: install a package
2. rpm -F packagename: reinstall a package
3. rpm -U packagename: upgrade a package
4. rpm -e package name: remove a package
5. rpm -qa list all packages that are installed on your system

YUM component acts as the front-end package installer for RPM

1. yum install R R-core R-core-devel R-devel //to install R in Linux/Centos