Open list of files particular protocol | lsof –i TCP,lsof –i TCP:80, |
list of open file particular service,user | lsof –c http,user |
Backup tar,gzip,bunzip2,cpio | tar –cvf backup.tar sourcefile file,bunizp2 sourcefile,find / -name *.c | cpio –o –format=tar cfile.tar |
RAID-3 , RAID -5 | Parity separate disk, parity across disk |
RAID -0,RAID -1 | Striping , mirroring, |
Iptables –chain –Accept-Reject-Drop, rules | -A,-s,-d,-p,-j,-i, |
Log file, | /var/log/messages,/var/log/lastlog,dmesg |
http log file | /var/log/httpd/error_log,/var/log/httpd/access_log |
Shutdown option | Shutdown –r,-f,-h |
Raid | Mdadm –c /dev/md0 –l1 –n2 –x1 /dev/had(1,2) |
Zombie Process | Kills –S SIGCHILD [processed], ps –el | grep ‘s’ |
/etc/passwd | Usernme:xyx:3:4:Commend:Home Directory:shell login |
/etc/fstab | /dev/sda3 /mnt ext3 defaults 1 0 deviceName MountPoint FileSystem mount optiong dumb fsck order |
Cut | Cut -d –f3,4 /etc/passwd |
Booting option | BIOS –MBR-kernel-init-Run Level |
Networkg monitor command | Netstat | Routing table,masquerade connection, Netstat –r,netstat –an | grep 80, Network statics netst -s |
Difference Between ext2 to ext3 file system | Availablity, Data Integrity, Speed, Easy Transition |
Ext2 to ext3 | Ext3 to ext2 | tune2fs –j /dev/hda1 | #tune2fs –O ^has_journal /dev/hda10 |
Port Number SSH-IMPAS-mysql-smpts | 22-993-3306-465- |
/proc File system | Details about kernel,Hardware,Running process /proc/PID, mdstat,cpuinfo,meminfo,modules ,mount,partition |
Kernel job | System initialization ,Memory Management, Network Management ,Security, |
Userid ,groupid, stick bit | setuid: chmod 4000 setgid: chmod 2000 sticky bit : chmod 1777 |
Sudo | /etc/sudoers,visudo , [username] [system name] = [paths] restart rhel5 sys1.redhat.com=/etc/httpd/restart |
vmstat | Monitor virtual memory Id-idle time wa –watingi for input Us-[user time] –time spending on kernel mode Sys-[sys time]-time spending on kernel mode |
Umask | Root 022 user 002 |
SERVICES | |
/usr/share/doc/dhcp-3.0.5/dhcpd.conf.sample | subnet 192.168.0.0 netmask 255.255.255.0 { -- line 4 range dynamic-bootp 192.168.0.128 192.168.0.254; –line 21 |
Web Server | /var/www/html /etc/httpd/conf/httpd.conf |
NIS | 1)install yp* package 2)add the /etc/sysconfig/network NIS Domain=rhel5 3)portmap & ypserv restart 4)Add Host /usr/lib/yp/ypinit –m 5)Add the user 6)/var/yp ->make client Add the NIS domain using setup 3) |
NFS | /etc/exports 2) restart 3)showmount –e ip |
User quota | 1)etc/fstab , usrquota , 2)mount –o remount /home 3)quotacheck –cf /home 4)eduquota –u username |
LVM Reduce or Extended | 1)resize2fs /dev/vg1/data 12M 2)lvreduce –L 12M /dev/vg1/data |
LVM Create | 1)pvcreate /dev/had6 /dev/hda7 /dev/hda8 2)vgcreate /dev/vg0 /dev/hda6 /dev/hda7 /dev/hda8 3)lvcreat –L 20M –n /dev/vg1/data |
ACL | 1)setface –m u:username:permission file |
Samba | 1)install samba* 2)add samba user 3)change ownership 4)create the samba password 4)/etc/samba/smb.conf,path,writable,read only |
Rsync | -e,-a.-z,-v,-=r |
TCP | Connection,3 way handshake,acknologment,low speed |
UDP | Connectionless protocol, no 3 way handshake ,no acknologment ,high speed DNS is Normally use UDP DNS,DHCP,TFTP |
Iptables | Iptables –A Input –s 0/0 –d 12.12.0.5 –p TCP –j ACCEPT |
Awk | ls –l | awk ‘{ print $3 }’ |
Df | Partition |
Du | Folder size |
Network Monitor Analysis | Monitor network traffic- capture Network Traffic |
Network | /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-IP Address |
Mysql | |
Request Time Out | Turn off firewall |
Destination Host unreachable | Maintain the Same IP |
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