linux administration

Linux Basic Commands-Memory related commands login to the unix/solaris server ip or host name Ex-   ip 10.1.21.1   host  usex10alg username: wesrg passwd         : ******* You will log in to the server. It will take you to default home_directory. - pwd it shows/prints the present working directory -ls -l gives listing of the files in present directory -cd .. takes you to previous directory mkdir <directory> will create directory  -mkdir -p /home/jb/j1/j2/j3 will create all the non-existing directories at a stretch -vi <file_name> opens file for reading/editing -cat <file_name> display contents of file -more <file_name> displays page by page contents of file -tail <file_name> shows last 10 lines of file use tail -f for continous update of file_name -head <file_name> shows first 10 lines of...

System Run level or INIT Process- INIT ·   Looks at the /etc/init tab file to decide the Linux run level. ·   Following are the available run levels   0 – halt   1 – Single user mode   2 – Multiuser, without NFS   3 – Full multiuser mode   4 – unused   5 – X11 Runlevel programs :   The Linux system is booting up, you might see various services getting started. For example, it might say “starting sendmail …. OK”. Those are the runlevel  programs, executed from the run level directory as defined by your run level.  Depending on your default init level setting, the system will execute the programs from one of the following directories.   Run level 0 – /etc/rc.d/rc0.d/   Run level 1 – /etc/rc.d/rc1.d/   Run level 2 – /etc/rc.d/rc2.d/   Run level 3 – /etc/rc.d/rc3.d/   Run level 4 – /etc/rc.d/rc4.d/   Run level 5 – /etc/rc.d/rc5.d/   Run level 6 – /e...

Linux Booting Process- Boot Process in Linux(Redhat Linux & CentOS ) Linux Boot Process: Press the power button on your system, and after few moments you see the Linux login prompt. Have you ever wondered what happens behind the scenes from the time you press the power button until the Linux login prompt appears? 6           6   high level stages of a typical Linux boot process- 1.     BIOS        Basic Input/Output System   Executes  MBR 2. MBR         Master Boot Record  Excutes     GRUB 3.  GRUB     Grand Unified Bootloader      Excutes Kernal 4. Kernal      Kernal Excutes   /sbin/init 5. INIT           ININT Excutes Runlevel program 6.Runlevel    Runle...