Linux Common Command

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Common command on Linux for operation and maintenance

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Linux Common Command

  1. 1. Linux Commands & Tools v1.3 j3ffyang at gmail
  2. 2. Environment Setting BaSH, Bourne Again SHell (Linux default), vs. Korn Shell (on AIX) Current env env System wide/ global /etc/bashrc -> aliases and functions (read always, login- shell and non-login-shell) /etc/profile -> env (read when login- shell) User base ~/.bashrc (/etc/bashrc read first, then ~/.bashrc) ~/.profile /etc/skel -> system level files copied to /home/user when created
  3. 3. Environment Setting Objective: Run WAS_installdir/bin/setupCmdLine.sh correctly Solution: #!/bin/sh (symlinked to /bin/bash) source /file (run in current shell) . file.sh (same as above) ./file.sh (run in child shell process) pstree
  4. 4. Hardware Specification Objective: How fast is CPU? How big is RAM? SWAP size? Solution: cat /proc/cpuinfo cat /proc/meminfo cat /proc/swaps
  5. 5. System Specification Objective: How to partition harddisk before installing WebSphere Commerce? Solution: /boot 100MB / 10G SWAP =<2 x RAM (usually 1~ 1.2G if RAM=1G) http://www.redhat.com/docs/manuals/enterprise/RHEL­4­Manual/pdf/rhel­ig­x8664­multi­en.pdf ­> page 28
  6. 6. Kernel - Messaging Objective: Optimize kernel for DB2. Solution: Display kernel parameter ipcs ­l Display kernel parameter Editing /etc/sysctl.conf kernel.msgmni = 512 kernel.sem=250  128000  32 1024 Activating kernel parameters sysctl ­p http://www­106.ibm.com/developerworks/linux/library/l­ss3­db2/
  7. 7. System Management Objective: Want to how the file system being used? Solution: du -cks $(ls -l | grep '^d' | awk '{print $9}') | sort -nr du -ksh
  8. 8. System Startup Objective: Switch between X startup and command line startup. Change the runlevel. Solution: cat /etc/inittab | grep “id”
  9. 9. System Mgmt - fuser Objective: Which process holds up the file? Solution: fuser pid [root@sevenj root]# fuser /var/log/messages /var/log/messages: 3292 User [root@sevenj root]# fuser -u /var/log/messages /var/log/messages: 3292(root) Terminate the processes that using file fuser -kimuv /path/file fuser -kxuc /path/file (on AIX) Port [root@sevenj root]# fuser 22/tcp 22/tcp: 3470
  10. 10. System Mgmt - lsof Objective: Which program is running over a port? Solution: lsof – LiSt Open File Which application is using port 22? lsof -i:22 [root@summerpalace /]# lsof -i:22 COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME sshd 3803 root 3u IPv4 3387 TCP *:ssh(LISTEN) sshd 30328 root 4u IPv4 2616339 TCP summerpalace.torolab.ibm.com:ssh->9.26.190.11:33875 (ESTABLISHED)
  11. 11. System Mgmt – lsof (cont'd) What files are opened by PID? [root@summerpalace /]# lsof -p 3803 COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME sshd 3803 root cwd DIR 3,2 4096 2 / sshd 3803 root rtd DIR 3,2 4096 2 / sshd 3803 root txt REG 3,2 280184 551800 /usr/sbin/sshd sshd 3803 root mem REG 3,2 51924 535486 /lib/libnss_files-2.3.2.so sshd 3803 root mem REG 3,2 1563240 1054615 /lib/tls/libc-2.3.2.so sshd 3803 root mem REG 3,2 5572 292096 /usr/kerberos/lib/libcom_err.so.3.0 sshd 3803 root mem REG 3,2 63880 292106 /usr/kerberos/lib/libk5crypto.so.3.0 sshd 3803 root mem REG 3,2 385220 292116 /usr/kerberos/lib/libkrb5.so.3.1 sshd 3803 root mem REG 3,2 971612 535528 /lib/libcrypto.so.0.9.7a sshd 3803 root mem REG 3,2 91368 535470 /lib/libnsl-2.3.2.so sshd 3803 root mem REG 3,2 52584 1216870 /usr/lib/libz.so.1.1.4 sshd 3803 root mem REG 3,2 12564 535504 /lib/libutil-2.3.2.so sshd 3803 root mem REG 3,2 76468 535498 /lib/libresolv-2.3.2.so sshd 3803 root mem REG 3,2 14728 535466 /lib/libdl-2.3.2.so sshd 3803 root mem REG 3,2 30448 535533 /lib/libpam.so.0.75 sshd 3803 root mem REG 3,2 28452 1216947 /usr/lib/libwrap.so.0.7.6 sshd 3803 root mem REG 3,2 106532 535453 /lib/ld-2.3.2.so sshd 3803 root 0u CHR 1,3 66540 /dev/null sshd 3803 root 1u CHR 1,3 66540 /dev/null sshd 3803 root 2u CHR 1,3 66540 /dev/null sshd 3803 root 3u IPv4 3387 TCP *:ssh (LISTEN)
  12. 12. System Mgmt – lsof (cont'd) What application is holding a dir and files under that dir? [root@summerpalace /]# lsof +d /var/log COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME syslogd 3676 root 2w REG 3,2 1393576 780963 /var/log/messages syslogd 3676 root 3w REG 3,2 925 780964 /var/log/secure syslogd 3676 root 4w REG 3,2 430 781130 /var/log/maillog syslogd 3676 root 5w REG 3,2 10246 781139 /var/log/cron syslogd 3676 root 6w REG 3,2 0 781134 /var/log/spooler syslogd 3676 root 7w REG 3,2 0 781138 /var/log/boot.log
  13. 13. System Mgmt – SWAP Objective: Want to change SWAP size? Solution: mkswap /dev/hdaX sync swapon /dev/hdaX cat /proc/swaps
  14. 14. System Mgmt – mkfs Objective: Create a file system? Solution: fdisk -l fdisk /dev/hda mkfs -t ext3 /dev/hdaX mkfs /dev/hdaX tune2fs -j /dev/hdaX (Convert ext2 to ext3. Journaled.) mount /dev/hdaX /mount/point Edit /etc/fstab /dev/hdaX /mount/point ext3 defaults 1 2
  15. 15. File - compression Objective: Compress/ Uncompress? The archive formats? Solution: Compress zip *.zip jar *.jar (same as zip) tar -czvf *.tar.gz bzip2 *.bz2 gzip *.gz / *.Z rar (http://www.rarlab.com/) Uncompress unzip jar -xvf tar -xzvf bunzip2 gunzip
  16. 16. File - editor Objective: Edit the file? Solution: vi kate (Similar to UltraEdit. Install kdebase*.rpm) jedit (http://jedit.org) emacs ed
  17. 17. Network Objective: Get the DHCP IP+ Register hostname in DNS Solution: /etc/sysconfig/network dhclient ethX /dhclient.conf (man dhclient.conf -> sample) YaST or YaST2 (Yet another Setup Tools) /etc/hosts Edit /etc/sysconfig/network-scripts/ifcfg-ethX Add DHCP_HOSTNAME=<your_hostname> Verification: hostname -s / -d nslookup / host / dig
  18. 18. Network - netstat Objective: Network status. Solution: TCP/IP netstat -pant netstat -pat
  19. 19. Network – http/ftp Objective: Run ftp client in command line? Solution: wget -t3 -c -r -l 10 http://domain.org -t= retry, -c= continue, -r= recursive, -l= depth (level of subdirectories)
  20. 20. Performance - Process Objective: The running processes' status? Solution: How much the CPU usage? ps auxwww | sort +2 -r ps -ef | sort +3 -r | head -n 5 How much the MEM usage? ps auxwww | sort +3 -r The process tree. pstree
  21. 21. Performance – Manage Srvc Objective: Turn on / off the unnecessary services. Solution: List all available services. chkconfig --list chkconfig –-list | grep 3:on Check on / out services. eg. chkconfig iptables on | off chkconfig –level 2345 iptables on less /etc/init.d/iptables ls /etc/rc.d/rc3.d Stop a service. eg. /etc/init.d/sshd start | stop
  22. 22. Performance - Memory Objective: System memory usuage. Solution: vmstat <interval> <length> eg. vmstat 1 10 [root@summerpalace root]# vmstat 1 10 procs memory swap io system cpu r b swpd free buff cache si so bi bo in cs us sy id wa 1 0 0 146512 107140 616064 0 0 4 17 105 30 0 0 99 0 0 0 0 146428 107140 616064 0 0 0 148 130 76 0 4 96 0 r: The number of processes waiting for run time. si / so: Swap in/ out bi / bo: Blocks in/ out us: User time sy: System time id: Idle Reference: What's block and character device? http://www.uwsg.iu.edu/usail/concepts/filesystems/everything­is­a­file.html
  23. 23. Performance - top Objective: Overall system performance. Solution: top s – interval in second M – sort by memory P – sort by CPU
  24. 24. RPM Objective: Manage the packages Solutions: RPM = RedHat Package Manager. Used by RedHat, SuSE and Mandrake. Debian dpkg converter is available. Install / Update rpm -Uvh package.rpm (vs. -ivh) rpm -Uvh package.rpm --nodeps rpm -Uvh –-aid package.rpm (require rpmdb-*.rpm installed) Uninstall rpm -e package_name rpm -e –-allmatches package (man rpm, search allmatches) RPM DB Rebuild db_verify /var/lib/rpm/Packages rpmdb --rebuilddb
  25. 25. RPM (cont'd) Solutions: Find an RPM rpm -qa | grep -i package_name Which rpm does a file belong to? rpm -qf /path/file The pre- requisite of an RPM? rpm -q –-requires mozilla Where is the RPM installed? rpm -qil mozilla Check RPM's changelog rpm -qi mozilla
  26. 26. MultiMedia :-) Objective: Have fun in work with Linux :-) Solution: xmms (Play MP3) grip (Rip wave to MP3) Make ISO file for burning disc mkisofs -r -o file.iso /path/files Test to mount mount -t iso9660 -o ro,loop=/dev/loop0 file.iso /mnt/tmp Scan CD writer cdrecrd -scanbus Write ISO to disc cdrecord -v speed=8 dev=0,0,0 -data file.iso GUI CD write -> http://www.xcdroast.org/ xcdroast

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