int questions

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Probably the simplest and most common way to do this would be by using the command:

tail -F $LOGFILE

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How To check Memory stats and CPU stats ?

Ans:  Using ‘free’ & ‘vmstat’ command we can display the physical and
virtual memory statistics respectively.With the help of ‘sar’ command we see the CPU utilization & other stats.
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Why is LVM is required ?
Ans: LVM stands for Logical Volume Manager , to resize filesystem’s size online we required LVM partition in Linux.
Size of LVM partition can be extended and reduced using the lvextend & lvreduce commands respectively.
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How to create partition from the raw disk ?
Ans: Using fdisk utility we can create partitions from the raw disk.Below are the steps to create partition from the raw dsik :
– fdisk  /dev/hd* (IDE) or /dev/sd* (SCSI)
– Type n to create a new partition
–  After creating partition , type w command to write the changes to the partition table.
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How to share a directory using nfs ?
Ans: To share a directory using nfs , first edit the configuration file ‘/etc/exportfs’ , add a entry like
‘/<directory-name>  <ip or Network>(Options)’ and then restart the nfs service.
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SMTP          25
DNS            53
FTP             20 (data transfer) , 21 ( Connection established)
DHCP         67/UDP(dhcp server) , 68/UDP(dhcp client)
SSH            22
Squid         3128
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How to check default route and routing table ?
Ans: Using the Commands ‘netstat -nr’ and ‘route -n’ we can see the default route and routing tables.
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How to check which ports are listening in my Linux Server ?
Asn:  Use the Command ‘netstat –listen’ and ‘lsof -i’
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How to upgrade Kernel in Linux ?
Ans: We should never upgrade Linux Kernel , always install the new New kernel using rpm
command because upgrading a kenel can make your linux box in a unbootable state.
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On Unix and Unix-like computer operating systems, a zombie process or defunct process is a process that has completed execution (via the exit system call) but still has an entry in the process table
Zombie processes should not be confused with orphan processes: an orphan process is a process that is still executing, but whose parent has died.
To remove zombies from a system, the SIGCHLD signal can be sent to the parent manually, using the kill command.
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There are three types of port forwarding with SSH:

Local port forwarding: connections from the SSH client are forwarded via the SSH server, then to a destination server

Remote port forwarding: connections from the SSH server are forwarded via the SSH client, then to a destination server

Dynamic port forwarding: connections from various programs are forwarded via the SSH client, then via the SSH server, and finally to several destination servers
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Using the command ‘vgcfgrestore‘ we can recover deleted LVM partitions. Linux keeps the backup copies of lvm configuration  in the/etc/lvm/archive directory.
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Example of searching files with size between 100 kilobytes and 500 kilobytes.
find . -size +100k -a -size -500k
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Note that -iname is not in the standard and may not be supported by all implementations.
find . -iname 'MyFile*'
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