Linux root user's manual

Change to root user

$ su - root Password : ******** #

Shutdownn

# halt

# shutdown -h now

Reboot

# reboot

# shutdown -r now

Make Group

staff:x:500: trainee:x:501:

Make General user. (This user can use telnet)

# useradd hoge -g staff # passwd hoge

Mount CD-ROM Drive

• Mount

  # mount /mnt/cdrom

• Unmount

  # umount /mnt/cdrom # eject

  cron - daemon to execute scheduled commands (Vixie Cron)

  # crontab -u root -e

  Edit like this

  0 4 * * * /root/bin/test

  Colums
  1	minute
  2	hour
  3	month
  4	year
  5	day of week(0:Sunday, 1:Monday, ...7:Saturday)

  rpm - Red Hat Package Manager

• Install

  # rpm -ivh package.rpm

• Install from source

  # rpm --rebuild package.src.rpm

• Update

  # rpm -Uvh package.rpm

• Uninstall

  # rpm -e package

• Installed packages list

  # rpm -qa | less

• See the pachage's information

  # rpm -qi apache

• See the pachage's file list

  # rpm -ql apache

• Query the package which contains the file

  # rpm -qf /etc/passwd setup-2.5.12-1

• See dependancies to install the pachage

  # rpm -q --requires apache # rpm -qR apache

• RPM packages's download site
  http://rufus.w3.org/linux/RPM/

  df - summarize free disk space

  # df Filesystem         1024-blocks  Used Available Capacity Mounted on /dev/hda7             256592  201147    42193     83%   / /dev/hda8             256592   74744   168596     31%   /home /dev/hda5            1732961  476993  1166408     29%   /usr /dev/hda6            1732961  430138  1213263     26%   /var

  bashrc - Login script

• /etc/bashrc

  # /etc/bashrc # System wide functions and aliases # Environment stuff goes in /etc/profile alias llmo="ls -lt | less" ................

  Add a new partition

  For example, adding a new disk and copy /usr directory to the new disk
  1. Change to a single user mode. This mode doesn't run any other user's task. This mode runs only root user's task.

     # init 1

  2. fdisk

     # fdisk

  3. format for ext2 file system

     # mkfs -t ext2 /dev/hdxx

  4. mount

     # mkdir /usr2 # mount -t ext2 /dev/hdxx /usr2

  5. copy files

     # cd /usr # tar cvf - . | ( cd /usr2; tar xpf - )

  6. Mount again

     # umount /usr2 # rmdir /usr2 # mv /usr /usr.bak # mkdir /usr # mount -t ext2 /dev/hdxx /usr

  7. Change multi user mode ([Ctrl]+[d]) and test some programs.

     # startx ...............

  8. edit /etc/fstab

     # cp -p /etc/fstab /etc/fstab.bak # vi fstab

  9. /etc/fstab

     /dev/hda1               /                       ext2    defaults        1 1 /dev/hdxx               /usr                    ext2    defaults        1 1 /dev/hda5               swap                    swap    defaults        0 0 /dev/fd0                /mnt/floppy             ext2    user,noauto     0 0 /dev/cdrom              /mnt/cdrom              iso9660 user,exec,noauto,ro 0 0 none                    /proc                   proc    defaults        0 0

  10. Reboot

      # shutdown -r now

  11. or mount -a

      # mount -a

  12. Remove old /usr directory

      # rm -fr /usr.bak

  13. Check new partition

      # df

  tar - tape file archiver

• Backup to a tape device

  # tar cvf /dev/rst0 /usr

• List the contents of an archive

  # tar tvf /tmp/etcbackup.tar

• Create a new archive

  # tar cvf /tmp/etcbackup.tar /etc

• Extract files from an archive

  # tar xvf /tmp/etc/backup.tar

• Create a new archive with compression

  # tar zcvf log.tar.gz log

• Extract files from a compressed archive

  # tar zxvf log.tar.gz

  compress - compress and expand data

• Compress

  # ls -lt test.tgz -rw-r--r--   1 root     root       604160 Aug 26 05:31 test.tgz # compress test.tgz # ls -lt test.tgz* -rw-r--r--   1 root     root        56373 Aug 26 05:31 test.tgz.Z #

• Expand

  # ls -lt test.tgz* -rw-r--r--   1 root     root        56373 Aug 26 05:31 test.tgz.Z # uncompress test.tgz.Z # ls -lt test.tgz -rw-r--r--   1 root     root       604160 Aug 26 05:31 test.tgz

  du - summarize disk usage

• /root/.bashrc

  ... alias dsk='du -ks * .* | sort -n' ...

  # cd /home # dsk du: ../proc/4620/fd/4: No such file or directory 1       samba 12      lost+found 386     hoge 1068    ftp 1541    httpd 3009    . 342510  .. # cd / # dsk du: proc/4622/fd/4: No such file or directory du: ./proc/4622/fd/4: No such file or directory du: ../proc/4622/fd/4: No such file or directory 0       proc 3       mnt 12      lost+found 39      dev 635     boot 654     root 1156    tmp 2245    sbin 2274    etc 3009    home 3871    bin 8919    var 12333   lib 307359  usr 342510  . 342510  ..

  e2fsck - check a Linux second extended file system

  e2fsck is used to check a Linux second extended file system.

   

• If you get these messages while booting your Linux box, use e2fsck command

  ... /dev/sdb1: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY. (i.e., without -a or -p options) ---------------------------------- *** An error occurred during the file system check. *** Dropption you to a shell; the system will reboot *** when you leave the shell. Givi root password for maintenance (or type Control-D for normal startup): Password # /sbin/e2fsck /dev/sdb1

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