This post lists common commands used in Windows and Linux/Unix system administration, server support, and troubleshooting.
Linux/Unix
The first command indicates the command name (searchable with a man page). The parens indicate useful extensions
File Searching, Browsing
| Command | Usage/Function |
|---|---|
| ls (-al) | List files and directories |
| find (./ -name or expression ‘in quotes’) -print | Find files given filename and other parameters.Some usage patterns are below.-exec is powerful since it defines what to do with the file(s) found by the find command. For example, you can use grep to look for information inside those files (see below). |
| find / -type f -exec grep -l “string_here” {} ; | Find files containing a string called “string_here” |
| find / -type f -print -exec grep -l “string_here” {} ; | >Find files containing a string called “string_here” and output the lines from those files that contain that string. -print will show which files were found. |
| find . -name ‘*s’ -print | To see which files within the current directory and its subdirectories that end in s |
| grep | Display files and extract information containing word / pattern after the command |
| egrep | Extract line containing word / pattern after the command |
| pwd | Print (output to console) current working directory |
| less, more | Console content control/reader |
| locate | |
| Cp | |
| mv | |
| Rm (-Rf) | Remove (with recursive and forced) |
ampersand (&) – Executed after a UNIX command makes the command run while providing the command prompt back. Using & allows you to continue to type more UNIX commands.
Common use of the ampersand ( & ) is at the end of commands that open their own windows like a web browser or an editor..
The amperand (&) means something different when used immediately after a greater than (>) for output redirection or after the pipe symbol ( | ) for passing output to other commands.
Utility
| Command | Usage/Function |
|---|---|
| cat | |
| man | Manuals (help pages) for system commands. |
| ln –s | Create symbolic links between files |
| touch | |
| ftp | File transfer protocol program |
| ping | |
| finger | |
| telnet | |
| ssh | Secure Shell |
| bash | Bash shell (running activates bash shell on console if it is available). |
| Rm (-Rf) | Remove (with recursive and forced) |
| nslookup OR dig OR host | Domain name service lookupdig -x <ip> or nslookup <ip> does reverse lookup |
| whois | Query |
| traceroute | Trace network route |
| lynx | Text based HTML browser |
| mount, unmount | Mount or unmounts file systems |
| date | Date/time on system |
| runmqsc (WebSphere Messaging Queue MQ) | ex. runmqsc <queue>
DISPLAY CHSTATUS(*) – display all channels info DISPLAY CHSTATUS(‘<queue>’) STOP CHANNEL(‘<queue>’) RESET CHANNEL(‘<queue>’) START CHANNEL(‘<queue>’) DISPLAY CHANNEL(‘<queue>’) |
| wget | GNU tool to retrieve web or file content. |
| Example of using wget to create of backup of a website (web archive) stored on your local computer. See the wget manual for more options.Get/backup website content for offline viewing:
[dark_box]wget -c -m -k -K -E -P/tmp http://url_of_the_website[/dark_box] Get/backup website content for offline viewing. Limit rate to reduce load on the target website and ignore robots file. Ignoring the robots file is helping for backuping up everything under a website and for WordPress blogs. [dark_box]wget -c -m -k -K -E -P/tmp –limit-rate=300k -e robots=off http://url_of_the_website[/dark_box] Here is what each option means:
|
|
System Administration
| Command | Usage/Function |
|---|---|
| prstat: report active process statisticssar: System activity reportermpstat : Report per-processor or per-processor-set statistics | Check CPU utilization, per CPU statistics. (e.g. sar 1, sar -u 10 60, mpstat 10 60)(e.g. Stats by zone: prstat -Z, Stats by Projects/users prstat -J) |
| useradd (Solaris) | Create a user Example: useradd -d /export/home/smithjo -m -k -s /bin/bash -c “John Smith” -g100 smithjo |
| userdel (Solaris) | Remove a user. Example: userdel -r smithjo The -r option removes the users home directory and login information |
| groupadd (Solaris) | Modify a user’s information like group |
| usermod (Solaris) | Modify a user’s information like group |
| rpm (Redhat based systems) | Package manager |
| ifconfig (-a) | Display IP address information including loopback and inet interfaces, sometimes in /usr/sbin |
| hostname (-f) | Obtain hostname information of server |
| domainname | Display a servers domain name |
| pkgadd (Solaris), yum (Fedora, RPM)package-cleanup | Package manager tools (e.g. yum install <program name> |
| chkconfig | |
| chownchmodchgrp | File ownership and rights management. E.g. chown <new owner> <filename>chmod 664 <filename> for rw-rw-r |
| File compressions and ExtractionCompressgzip -c file1 file2 > foo.gztar cf – target_file_or_directory | gzip -c > target.tgzgtar -cvzf target output.tgzUncompressgzip -dc output_file.tar.gz | tar -xf – | Related commandsCreate a tar file:tar cvf <tar.filename> <files.to.tar.up>Extract a tar file:tar xvf <tar.filename>Check the contents of a tar file:
tar tvf <tar.filename>tar (-xzif) Unzip unzips a zip filegunzip :unzips tar.gz files |
| sendmail | Mailer |
| Email management | |
| head | |
| tail (-f) | See near end of file or stream file with -f |
| passwd | User password management |
| su | Assume root user or user specified after command. Will prompt for password. |
| sudo | Assume root user only for command following sudo. Will prompt for password. |
| last | |
| who | |
| df (-akh) | Reports on disk space on mounted and mounted file systems |
| md5 | Checksum command |
| cron | Scheduler |
| uname (-a) | System/machine information |
| ps (-ef) (-Al) | List (all) processes and their details |
| xinetd | |
| kill (-HUP) | Send signals to process. E.g. kill -9 <pid> kills a process with pid specified |
| shutdown (now) (-r) | Shutdown operating system e.g. -r restart afterwards “now” shuts the system down right away without a time delay |
| netstat (-an) | Network information for system, port listeners and addresses. E.g. netstat –rn to view existing kernel IP routing table |
Programming
| Command | Usage/Function |
|---|---|
| gcc (or cc) | C compiles |
| pico, nano | File editors |
| make | Builder program |
Useful Concepts for Linux/Unix
Directory Structure
Logs, spoools, and file resources (mail, logs, temp, etc.): /var
Configuration Files: /etc, /etc/rc.init (startup scripts). /etc/sendmail.cf
Unix “blackhole”: /dev/null
Core Command locations if not in path: /usr/(s)bin, /usr/local/(s)bin, /usr/sfw/bin/ | Solaris: /usr/openwin
Devices (I/O): /dev
Mounted Systems: /mnt, /media
Code Libraries/Modules: /usr/lib, /usr/local/lib
Stored source: /usr/src
**Services: **/etc/services – example of entries in services file (ports and protocols associated with the ports.
netstat 15/tcp
ftp 21/tcp # File Transfer
ssh 22/tcp # Secure Shell
telnet 23/tcp
Platform Specific
User settings ~/.<user setting folder>
e.g. ~/.kde/share/apps stores KDE desktop settings and configurations.
Checking serviers and ports in netstat
less /etc/services | grep <service name>
netstat -a | grep <service name>| grep <keyword, e.g. LISTEN>
Checking Memory
Check Total physical memory:
# prtdiag -v | grep Memory # prtconf | grep Memory
Check Free physical Memory:
# top (if available) # sar -r 5 10 Free Memory = freemen*8 (pagesize=8k) # vmstat 5 10 Free Memory = free
For swap:
# swap -s # swap –l
Windows
| Command | Usage/Function |
|---|---|
| certmgr.msc | Certificates |
| ciadv.msc | Indexing Service |
| comexp.msc | Component Services |
| compmgmt.msc | Computer Management, central administration panel for Windows. Can also be used to access IIS administration console. |
| control mouse | Open control panel for mouse |
| defrag, dfrg.msc | Disk Defragmenter |
| devmgmt.msc | Device Manager |
| diskmgmt.msc | Disk Management |
| eventvwr.msc | Event Viewer |
| fsmgmt.msc | Shared Folders |
| gpedit.msc | Group Policy |
| lusrmgr.msc | Local Users and Groups |
| msconfig | Startup files and processes configuration |
| ntmsmgr.msc | Removable Storage |
| ntmsoprq.msc | Removable Storage Operator Requests |
| perfmon.msc | Performance monitor |
| regedit | Registry editor |
| rsop.msc | Resultant Set of Policy |
| sc query | Find function. E.g. Find a Windows services called “WSearch”sc query | FINDSTR /i /r WSearch |
| secpol.msc | Local Security Settings |
| services.msc | Services and Process manager |
| wab | Windows address book |
| wmimgmt.msc | Windows Management Infrastructure (WMI) |
Remote Desktop Management related commands
ERROR The terminal server has exceeded the maximum number of allowed connections
If you encounter this error, you can either reboot the terminal server you are trying to remote desktop to or log into the machine as an administrator.
To log in as the administrator:
mstsc /v:<ip address e.g. 192.168.2.32) /console
By using /console at the end of the command you will be logging in as if you were at the server. Alternatively, if you are using Windows Server 2003, run this comment instead (replace /console with /admin)
mstsc /v:<ip address e.g. 192.168.2.32) /admin
If you can telnet or ssh to the server you can use the following command. This command will kill all active RDP sessions to free one so you can connect.
tsdiscon /1
tsdiscon /2
tsdiscon /3
tsdiscon /4
Session cleanup
When you execute the commands above, log in as an administrator on the machine. That log in allow you to use the console on the server.
Remove any disconnected users via the Terminal Services Manager
Start > All Programs > Administrative Tools > Terminal Services Manager
Click on the name of your server and the right side should show a list of users. If the users are disconnected, reset the users to free up the two normal remote desktop connections. Right clicking the disconnected user and selecting “Reset.”
It is good practices to only use the console to disconnect inactive sessions and not for anything else. Make sure you disconnect inactive user sessions first with the instructions above, otherwise if you get disconnected again you will have to physically access the server.
Remote Desktop sessions should always be closed using the Windows <<Log Off>> function rather than disconnecting by closing the window as using the X to close will disconnect from the session but leave it active.
References
Random thought
Despite carefully following installation and configuration procedures for various programs, they still tend not be smooth.
Justin Tung 