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Unix/Linux. Contents. Unix file system introduction Unix Common commands useful tips sharing snoop tool / tcpdump Set env. variables trouble shooting/diagnose (solaris) Diff b/w Linux and unix. Unix system structure. / (root). lib. tmp. bin. var. dev. lib. usr. root. boot.

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  • Unix file system introduction

  • Unix Common commands

  • useful tips sharing

  • snoop tool / tcpdump

  • Set env. variables

  • trouble shooting/diagnose (solaris)

  • Diff b/w Linux and unix

Unix file system hierarchy

/ (root)



























UNIX File system Hierarchy

Unix common commands
Unix common commands

  • Files commands grep,find,tail,ln,diff,tar/gzip,chmod,chown

  • System commands


  • Process commands


Grep egrep fgrep display lines that match
grep/egrep/fgrep–display lines that match

  • grep [options] regexp [files...]


    grep '^\.' myfile.txt

    grep –i “exception” */*

    find . |xargs grep -i “exception" #

    ls –al|grep ‘^d’ # List the directory in currect path:

  • fgrep --It does not use regular expressions; instead, it does direct string comparison to find matching lines of text in the input.

  • egrep --Search a file for a pattern using full regular expressions

Find find files matching a type or pattern
find--find files matching a type or pattern

  • find directory [options] [actions] [...]

  • e.g.

  • find . -name hello -print #

  • find . –mtime +7 –print # list the files modified 7days ago

  • find . –size +2000m –print #list the files larger than 2000m

  • find /tmp –user b123 –print#print the files belong to b123 user under tmp.

  • find . -name "*.php" –exec/ok rm {} \;# find and remove this php files

    or find . –name “*.php” |xargs rm

Tail ln diff

  • tail --display the last few lines (or parts) of a file.

    tail [options] file


    tail –f filename #display last 10 lines

    tail –5f filename # display last 5 lines

  • ln--link the source_file to the target

    ln [options] source target

  • diff --compare the two files and display the differences (text files only)

    diff file1 file2

File archiving compression tar gzip gunzip
File Archiving, Compression--- Tar/gzip/gunzip

  • tar [options] [directory file]

    gzip [options] file

    gunzip[options] file

  • Extract from an archive

    gunzip backup.tar.gz

    or tar -xvf backup.tar

  • Create an archive:

    tar -cvf backup.tar /etc #backup.tar

    gzip -q backup.tar #backup.tar.zip

  • tar –tf backup.tar #list the files in archive

Chmod chown chgrp

  • chmod --- change file permissions

    chmod nnn [argument list] numeric mode

    chmod [who]op[perm] [argument list] symbolic mode

    chmod u+xrw file

    chmod g+x file

    chmod o-rw file

    chmod 750 file

  • chown change the ownership of a file

    chown[options] user[:group] file

  • chgrp change the group of the file

Df du

  • df --summarize disk block and file usage

    df [options] [resource]

    Common Options

    -l local file systems only

    -k report in kilobytes

  • du report disk space in use

    du [options] [directory or file]

Ps top kill nohup
ps,top,kill, nohup

  • ps --Show status of active processes

    ps –ef|grep ems

  • Kill --terminate a process

    kill [-signal] processID

    kill –l #displays the available kill signals

    kill -9 processID #kill the processId of process

  • Top/topas/prstat --display all running processes

  • nohup --Runs a command even if the session is disconnected or the user logs out

    nohup find -name '*' -size +1000k > log.txt


  • Crontab -- List of files that you want to run on a regular schedule.

    crontab –l ; crontab -e

  • All crontab files are maintained in the /var/spool/cron/crontabs in solaris.

  • These first five fields are separated by spaces and indicate when the command will be executed.

    10,20 3 * * 0 /usr/sbin/log/adm

Unix linux

ifconfig--allows the operating system to setup network interfaces and allow the user to view information about the configured network interfaces

  • ifconfig eth0 # View the network settings on the first Ethernet adapter installed in the computer.

  • ifconfig –a #display into on all network interfaces on server, active or inactive.

  • ifconfig eth0 down #If eth0 exists would take it down causing it cannot send or receive any information.

  • ifconfig eth0 up #If eth0 exists and in the down state would return it back to the up state allowing to to send and receive information.

  • ifconfig eth0 netmask broadcast #Assign eth0 with the above values for IP, netmask and broadcast address.

Netstat shows network status
netstat -- Shows network status.

  • netstat #Displays generic net statistics of the host you are currently connected to.

  • netstat –an #Shows all connections to the server including the source and destination ips and ports if you have proper permissions.

  • netstat –rn #Displays routing table for all ips bound to the server.

  • netstat -an |grep :80 |wc –l #Display the amount of active connections on port 80. Removing the pipe and wc command would display each connection.

  • netstat –natp #Display active Internet connections.

Route show manipulate the ip routing table
route -- Show / manipulate the IP routing table

  • route –n #Shows routing table for all IPs bound to the server. (linux)

  • route add -net netmask dev eth0 #adds a route to the network 192.56.76.x via "eth0". The Class C netmask modifier is not really necessary here because 192.* is a Class C IP address. The word "dev" can be omitted here.

  • route add -net netmask dev eth0 #This is an obscure one documented so people know how to do it. This sets all of the class D (multicast) IP routes to go via eth0". This is the correct normal configuration line with a multicasting kernel.

Mount umount swap

  • Mount --- mount a partition

    mount -F hsfs -o ro /dev/dsk/c0t6d0s0 /cdrom

    mount -F pcfs /dev/diskette0 /floppy

    mount /dev/dsk/c0t0d0s0 /tmp/xxx

  • umount -- Unmount a partition

    umount /cdrom

  • swap

    mkfile 10G /home/swapfile

    /usr/sbin/swap -a /home/swapfile

    /usr/sbin/swap –l

    /usr/sbin/swap –d /home/swapfile

    rm -rf /home/swapfile

Redirection <, >, >>,|,;

  • Pipe | :The output of the first command is sent as the input to the second command, and so on,

    who | more

  • ; Grouping commands

    %pwd; cal 1 2000; date

  • >> append the results of the command to the existing file.

  • > The results of the command will be sent to the specified file

Set env variables
Set env. variables

  • .profile

    /etc/profile /root/.bash_profile /home/abc/.bash_profile

  • Commands set –local variable

    env –global variable

  • add variables to .profile


    export MOT_NSM_HOME

  • Re-logon, the variable will take effect.

Other useful commands tips
Other useful commands tips

  • converts Unix text file line to Dos

    unix2dos : sed –e ‘s/$/\r/’ file1 > file2

    dos2unix : sed –e ‘s/.$//’ file1 > file2

  • How to remove ^M in the file

  • # cat test.dat | tr -d '\015' > test.out

  • or #dos2unix test.dat test.out

  • watch –n N command(linux) #

  • init 0 ~6

  • init 0 shutdown server

  • init 6 restart server

  • vi filename1 filename2 …

    :n #edit next file

    :e# # edit prev file

    :1,$s/ABC/abc/g #abc to replace ABC in file

Snoop solaris xcapturing and inspecting network packets
Snoop(solaris) –xcapturing and Inspecting Network Packets

  • to see what happens when one system uses the ping command to communicate with another system.

  • %snoop sys41 sys42

    sys41 -> sys42 ICMP Echo request

    sys42 -> sys41 ICMP Echo reply

  • Use the -a option to enable audible clicks, which notify you of any network traffic.

    %snoop -a dhcp

  • shows how to turn on audible clicks for all network traffic related to a Dynamic Host Configuration Protocol (DHCP) boot.

Touble shooting diagnose 1
Touble shooting/diagnose (1)

  • 1.  How to setup solaris network. We usually meet the following problem

    1.1 how to config the IP,gateway, router,netmask, both dynamicly and staticly?

    Please add a file named S* in /etc/rc2.d/,such as S99router

    The content of this file is a command to exec

    1.2 how to add multi virtual IP to a single interface?

    • #ifconfig bge0:100 plumb

    • #ifconfig bge0:100 netmask up

    • #ifconfig bge0:100 unplumb

      1.3 how to disable certain network interface for test?

    • ifconfig eth0 down

Touble shooting diagnose 2
Touble shooting/diagnose (2)

  • 2. root user can't telnet on a remote client.

    Edit /etc/default/login and comment out “CONSOLE=/dev/console”

  • 3. root user can't ftp on a remote client

    Edit /etc/ftpd/ftpusers and comment out “root”

  • 4. how to monitor the performance of the Solaris/Linux, including MEM,CPU,disk I/O, network I/O

Touble shooting diagnose 3
Touble shooting/diagnose (3)

  • 5. Certain Solaris command cannot be used

        1) Check disk space to confirm whether there is the capacity of any filesystem is 100% #df –h

        2) Check the permission of some important directories. The directories must exist and have “x” permission./usr, /etc/ssh, /bin, /usr/bin

  • 6. forget the root passwd

    #boot cdrom -s #mount /dev/dsk/c0t0d0s0 /mnt #cd /mnt/etc #vi shadow #umount /mnt 

Touble shooting diagnose 4
Touble shooting/diagnose (4)

  • 7. If we meet system issues, such as the whole system can't boot. how to sovle? and how to collect the important saloris info(explorer)

  • 8. Why some user can't excute command cron and at to schedule a task?

  • 9. what's the difference between halt/reboot/shutdown/init #(# refers to a run level). what's the right step to reboot a system?

Touble shooting diagnose 5
Touble shooting/diagnose (5)

  • 10. how to kill a service in solaris 10? (SMF related)

    Please use “svcs disable “, not the “kill -9”

  • 11. how to delete temp file effectively? the following two commands are useful for programmers to delete certain files

        #find $HOME/. -name *.txt -ok rm {} \

         #find . \( -name a.out -o -name '*.o' -o -name 'core' \) -exec rm {} \

  • 12. what's the difference between the two command "#./set_env" and "#. ./set_env"?

    • The parent shell can get the env set by the child shell

Touble shooting diagnose 6
Touble shooting/diagnose (6)

  • 13. Nov 20 15:25:04 unix /usr/lib/snmp/snmpdx: [ID 702911 daemon.error] unable to get my IP address: gethostbyname(unix) failed [h_errno: host not found(1)]

    • Please add the hostname to hosts file

    • #nodename


    • #vi /etc/hosts127.0.0.1       localhost       unix    loghost

  • 14. Nov 20 15:36:32 unix ip: [ID 482227 kern.notice] ip_arp_done: init failed

    • Don’t use the interface name as the hostname

Touble shooting diagnose 7
Touble shooting/diagnose (7)

  • 15. Nov 20 15:37:21 unix sendmail[318]: [ID 702911 mail.crit] My unqualified host name (localhost) unknown; sleeping for retry

    • You should edit /etc/hosts like this, please note the FQDN and loghost outer   outer.c204.comloghost

    • svcs disable /network/smtp:sendmail

Touble shooting diagnose 8
Touble shooting/diagnose (8)

  • 16. When use “crontab -e” to add a cronjob, we can’t see the content of the cron table


    #export EDITOR

  • 17. When connect via console, and edit a file with vi, we can only see part of the file

    $ TERM=VT100

    $ export TERM

Diff b w linux and unix
Diff b/w linux and unix

  • Linux –free and open source, just kernel, based on UNIX standards, runs on many hardware platforms.

  • Unix --compete operating system, commercial application (if you wanted to buy one) typically costs much more for a commercial UNIX , a typical UNIX is proprietary-hardware-bonded.

The linux proc file system
The Linux Proc File System

  • The proc file system does not store data, rather, its contents are computed on demand according to user file I/O requests

  • Proc is organized in virtual directories and subdirectories, provide hardware information, such as /proc/cpuinfo, /proc/meminfo, and /proc/interrupts. The files under /proc/sys are related to kernel configuration parameters.

  • The /proc special directory provides full detailed information about the inner workings of Linux and lets you fine-tune many aspects of its configuration. If you spend some time learning all the possibilities of this directory, you'll be able to get a more perfect Linux box.

Linux versions study website
Linux versions/study website

  • Redhat http://www.redhat.com

  • Fedora (cover many features of windows) http://fedora.redhat.com

  • 红旗LINUX (China) htt://www.redflag-linux.com

  • SUSE Linux http://www.opensuse.org

  • Mandrake Linux http://www.mandriva.com