Linux & Unix (Ubuntu,Debian,RedHat,Centos)

Principles of Network and System Administration,

What is network and systemadministration?,
Applying technology in an environment,
The human role in systems,
Ethical issues,
Is systemadministration a discipline?,
the challenges of systemadministration,
Common practice and good practice,
Bugs and emergent phenomena ,
Themeta principles of systemadministration ,
Knowledge is a jigsaw puzzle,
To the student ,
Some road-maps

Apple file systems

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Apple Filesystems

MFS The Macintosh Filesystem (MFS) was used by the earliest Macintoshes. It’s almost never used on anything but 400KB floppy disks, which are extremely rare today. Linux does not include MFS support.

HFS The Hierarchical Filesystem (HFS) was the replacement for MFS. Used on 800KB and larger floppy disks and all Macintosh hard disks until 1998, HFS is quite common in the Macintosh world.

HFS+ The follow-on to HFS borrows many features from Unix-style filesystems, but it stops short of adding a journal. New Macintoshes invariably ship with their disks formatted for HFS+, but this filesystem is not used much on removable media.

FFS MacOS X provides the option to use the Unix Fast Filesystem (FFS), which is described in the next section. Many MacOS X systems continue to use HFS+, though.

 

 

chmod command

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chmod

chmod [options] mode(s) filename(s) chmod [options] octal_mode(s) filename(s)

The chmod command is used to change the access mode of files. Only the owner of the file or the superuser may alter its access. There are two methods for expressing the mode you wish to assign. The first is the symbolic method, wherein you specify letters representing the mode. This requires that you specify the following information.

Who is affected:

u User who owns the file
g Group (only users in file’s group)
o Other users
a All (default)

What operation:

+ Add permission
– Remove permission
= Set permission, overwriting old permissions

What kind of permission:

r Read
w Write
x Execute
s User or group ID is temporarily replaced with that of the file
t Set sticky bit: keep executable in memory after exit

RedHat Linux system proc files contents, descriptions

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File Contents
/proc/interrupts IRQ information
/proc/cpuinfo CPU information
/proc/dma DMA information
/proc/ioports I/O information
/proc/meminfo Available, free, swap, and cached memory information
/proc/loadavg System load average
/proc/uptime Time since last reboot
/proc/version Information about kernel version
/proc/scsi Information about SCSI devices
/proc/ide Information about IDE devices
/proc/net Network information
/proc/sys Kernel configuration parameters

Unix System Formatting Tools –

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 Formating Tools

Table 7. Formating Tools

Tool Requirements Description
e2fsck Included in tomsrtbt-1.6.335 Checks an ext2 filesystem for errors
format Included with Windows 95 and Windows 98 Creates a vfat filesystem on a chosen partition
mke2fs Included in tomsrtbt-1.6.335 Creates an ext2 filesystem on a chosen partition.
mkswap Included in tomsrtbt-1.6.335 Creates a swap filesystem on a chosen partition.

Restore grup boot loader after installing windows 7 and 8

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Boot-Repair is a simple tool to repair frequent boot issues you may encounter in Ubuntu like when you can’t boot Ubuntu after installing Windows or another Linux distribution, or when you can’t boot Windows after installing Ubuntu, or when GRUB is not displayed anymore, some upgrade breaks GRUB, etc.

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Remark: this can also be performed from a live-CD or live-USB.

Either add ‘ppa:yannubuntu/boot-repair’ to your Software Sources via the Software Centre or, for speeds-sake, add it using a new Terminal session:

Boot-Repair can be installed & used from any Ubuntu session (normal session, or live-CD, or live-USB). PPA packages are available for Ubuntu 10.04, 10.10, 11.04, 11.10, 12.04 and 12.10.