Linux Common Command
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This document provides solutions to common Linux commands and tasks. It covers topics such as environment setting, hardware and system specifications, file editing and compression, networking, performance monitoring, package management with RPM, and multimedia. Solutions are provided for tasks like changing the startup runlevel, monitoring swap size, editing files, getting the network IP and registering the hostname, and burning discs.
![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](https://image.slidesharecdn.com/linuxcmdtool-140711211437-phpapp02/85/Linux-Common-Command-9-320.jpg)
![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)](https://image.slidesharecdn.com/linuxcmdtool-140711211437-phpapp02/85/Linux-Common-Command-10-320.jpg)
![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)](https://image.slidesharecdn.com/linuxcmdtool-140711211437-phpapp02/85/Linux-Common-Command-11-320.jpg)
![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](https://image.slidesharecdn.com/linuxcmdtool-140711211437-phpapp02/85/Linux-Common-Command-12-320.jpg)
![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](https://image.slidesharecdn.com/linuxcmdtool-140711211437-phpapp02/85/Linux-Common-Command-22-320.jpg)
Linux Common Command
- 1. Linux Commands & Tools v1.3 j3ffyang at gmail
- 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. 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. Hardware Specification Objective: How fast is CPU? How big is RAM? SWAP size? Solution: cat /proc/cpuinfo cat /proc/meminfo cat /proc/swaps
- 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. 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. 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. System Startup Objective: Switch between X startup and command line startup. Change the runlevel. Solution: cat /etc/inittab | grep “id”
- 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. 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. 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. 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. System Mgmt – SWAP Objective: Want to change SWAP size? Solution: mkswap /dev/hdaX sync swapon /dev/hdaX cat /proc/swaps
- 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. 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. File - editor Objective: Edit the file? Solution: vi kate (Similar to UltraEdit. Install kdebase*.rpm) jedit (http://jedit.org) emacs ed
- 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. Network - netstat Objective: Network status. Solution: TCP/IP netstat -pant netstat -pat
- 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. 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. 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. 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. Performance - top Objective: Overall system performance. Solution: top s – interval in second M – sort by memory P – sort by CPU
- 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. 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. 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