Sunday, November 30, 2008

Linux Basics(1 of 6)

Linux Basics(1 of 6):

UNIX Standards:

BSD
SYSTEM V (system 5)

BSD:
Free BSD
Open BSD
Net BSD

SYSTEM V:

Solaris (Developed by SUN Microsystems)
HP-UX (Developed by HP)
SCO

There are some UNIX versions that folow some good features from BSD standard and some from
System v standard they can be named as Hybrid Unix Like:

LINUX
AIX

FILE TYPES IN LINUX:

In Linux/Unix every thing is treated as a file and every thing is represented by a file. Even devices
are represented by device files. There are four types files in Linux/Unix

1. Normal File:
Every file that contains data in it is caled normal file. E.g. execute able files,
Text files, movie files, audio files and Virus files etc.etc.

2. Directory File:
These are container files that hold other file and directories.

3. Link File :
These are like short cuts in windows. These just point towards the actual file.

4. Device File:
These represent devices. When ever we need to access a device we use these
files and these files gets the job done for us. These are present in /dev
directories.

THREE ROOTs IN LINUX/UNIX:

Word root is used for three entities in Linux/Unix

root user: Admin user of Unix/Linux systems is root user.
/root directory: Home directory of root user.
/: / is like my computer in Windows. It is the parent directory of al linux system.
Every thing is present under this directory

Note: Linux/Unix is case sensitive in every thing from username and password to parameters of file and command options.

8 comments:

  1. clarification regarding root user: as root user is an admin user in linux ... so is there any way we can create/convert normal user to admin user ??///.

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  2. clarification reagarding root user:
    root user(i.e the admin user) is the user with UID=0(zero).i.e if we set the UID of a normal user, lets say "pinku" to 0(zero), then the user "pinku" becames the admin user.

    hence one line in the post "root user: Admin user of Unix/Linux systems" must be read as "root user(user with UID=0): Admin user of Unix/Linux systems"

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  3. is there any way to stop the single user mode in
    linux so that i can stop root password change

    ReplyDelete
  4. @sameer:

    yes it is possible. u can password protect "grub" and thus restrict passing of any parameters at boot time. but it will cause restriction on all parameters and not just the "single user mode" parameter.

    and if u want to restrict "runlevel 1" then edit "/etc/init.d/initscript" and change the default runlevel to 3 or 5 as per your choice.

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  5. thanx for the reply
    can we not remove single user mode completely?

    ReplyDelete
  6. i'm not sure about that. but widout grub passwd u will not be able to pass any parameters to kernel at boot time

    ReplyDelete
  7. why can not c:drive in windowsXP support
    NTFS file system,is it a problem recovered by service packs

    ReplyDelete
  8. i got the answer thank you !
    http://support.microsoft.com/kb/822800

    ReplyDelete