Hard link: $ln source dest
By using hard link, all links and original file have the same inode.
Using ls command to list link information:
$ls –i test
$ls –l test : second column shows the number of links
Symbolic links: $ln –s source dest
For symbolic link, all links have different inode, user can create a symbolic link to a file that doesn’t exist.
Commands: ps, ps –aux, fg, bg, CTRL-Z(suspend job), jobs, kill %i (after % is job number)
Using /dev/null to redirect useless output data.
Stop and restart jobs:
CTRL-Z: suspend job;
$fg: restart job in the foreground;
$bg: restart job in the background;
$&: start job as background process.
Booting the system:
1. Make boot device manually
$rdev kernel-name root-device à to make boot partition
$rdev /vmlinuz /dev/hda2
$cp /vmlinuz /dev/fd0
2. Using LILO
Win95 installer will overwrite LILO MBR, before install win95, create boot disk for linux, install win95, then reboot with linux floppy, run /sbin/lilo, reconfigure the system.
Using $sys a: c: /mbr to overwrite LILO.
$shutdown hh:mm:ss(time) warning-message
$shutdown –r 20:00 we are shutting down -r means reboot the system after shut down.
The /etc/inittab file:
System boot, kernel mount the root file system, executes init that takes /etc/inittab as the parameter file, spawns a lot of children processes.
Managing the file system:
1. mounting the file system
$ mount –av
2. /etc/fstab file
File systems support by linux: ext2, ext, minix, xia, umsdos, msdos, proc, iso9660, xenix, sysV, coherent, hpfs
Linux uses ext2 as natural file system, swap partition has a mount point of none.
$ swapon –a
$ mount –t ext2 /dev/hda3 /usr
3. Device Diver name:
hdx: IDE driver sdx: SCSI driver
fdx: floppy driver stx: SCSI tape driver
scdx: SCSI CD-ROM driver
/dev/hda: the whole first IDE driver
/dev/hda1: the first partition in the driver
/dev/hda2: the second partition in the driver
/dev/hda: IDE, master, primary
/dev/hdb: IDE, slave, primary
/dev/hdc: IDE, master, secondary
/dev/hdd: IDE, slave, secondary
Checking the file sytem:
$e2fsck –av /dev/hda2
$efsck $xfsck $fsck
If e2fsck reports it performed repairs on a mounted file system, you must reboot the system immediately.
Using a swap file:
Create a swap file: $dd if=/dev/zero of=/swap bs=1024 count=8208 : create one 8M swap file
$mkswap /swap 8208
Drawback using a swap file:
1. Performance will not be as good as swap partition whose blocks are contiguous, I/O requests are made directly to the device;
2. System has more chance to corrupt for large swap file.
1. User can use swap file for the actions that need more swap space, and after that delete it.