Tricks for useful Linux Command

     

                Linux command

                                    

Mount a pen drive in Linux

root@server~# lsusb   or    # fdisk -l

root@server~# mkdir /mnt/pendrive

root@server~# mount <pen drive name><mount point> point)

root@server~# cd /mnt/pendrive

To mount a CD/DVD ROM drives in Linux.

The CD/DVD ROM device name in Linux is /dev/cdrom

root@server~# mkdir /mnt/mycdrom    (to create the mount point for CD/DVD)

root@server~# mount /dev/cdrom /mnt/mycdrom     (to mount the CD/DVD on the above created mount point)

root@server~# cd /mnt/mycdrom   (to access the CD/DVD ROM drives)

To mount the " .iso " image files in Linux .

root@server~#  mount -t iso9660 /root/rhel6.iso /iso -o ro, loop
                                                                                  (to mount the .iso image files)
root@server~#  cdrecord /root/Desktop/rhel6.iso

                                                     (to write the CD/DVD ROM. Before executing this
command put the empty CD/DVD into CD/DVD drive)

root@server~#  eject                                          (to eject the CD/DVD drive tray)

root@server~#  eject -t                       (to insert and close the CD/DVD drive tray)

Disk is full?

How to troubleshoot ?

First check which files are accessing more disk space by

                                           #du -h |sort - r

This command is show space in server.

So you can remove temporary and junk files from  disk and  make a room for new or updated data.

Disk space issues can we normally get

(i) Disk is full.
(ii) Disk is failing or failed.
(iii) File system corrupted or crashed.
(iv) O/S is not recognizing the remote luns when scanning, ...etc.,

System is continuously rebooting. How to troubleshoot it?

(i) Connect the system through console port through putty by providing IP address, user name and password.

(ii) At console prompt and boot with CDROM in single user mode and mount the root ( / ---> O/S) file system on temporary mount point.

(iii) Check any wrong entries in the cron jobs ie., crontab editor see any reboot scripts are there or not. If found remove those entries and reboot the system.

(iv) If the above is not resolved, then check the memory (RAM).

(v) If RAM module is not working the system get panic and it may continuously reboots.

(vi) If the RAM module is working then check the RAM size whether the sufficient RAM that requires to run the application is available or not. If not there then increasing the RAM size may be resolve this issue.

(vii) Check "/var/log/messages" file for any messages regarding continuous rebooting