Feb
22

How to find large files and directories in Unix/Linux

Adnan Khurshid on February 22nd, 2011

Finding large files: Suppose we are facing a disk space issue in one system user directory and we want to find out which files are using most of the disk space, we can run the following command to find it out: <36 SMSC :/export/home2/mml/tmp> find /export/home2/mml/ -size +400000| sort –r| head –3 /export/home2/mml/sms/bin/core_20110119152929_14771 /export/home2/mml/sms/bin/core_20101231115847_13489 /export/home2/mml/sms/bin/core_20101204105309_5074 […]

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Feb
18

How to determine which processes are taking most of your CPU and Memory in Linux

Adnan Khurshid on February 18th, 2011

Well, we know that command ‘ps –aux’ will show all the processes currently running on the system. We can sort the output of this command by using sort command piped after ps. We discussed about sort command before, you might want to have a look at it here. Lets first check the output of ps […]

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Feb
17

How to get columns from editor segregated by a delimiter in Linux

Adnan Khurshid on February 17th, 2011

This will be more understandable if we take it by an example. Let’s see how many users we have on the system: linux:~ # cat /etc/passwd root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/bin/bash daemon:x:2:2:Daemon:/sbin:/bin/bash lp:x:4:7:Printing daemon:/var/spool/lpd:/bin/bash mail:x:8:12:Mailer daemon:/var/spool/clientmqueue:/bin/false news:x:9:13:News system:/etc/news:/bin/bash uucp:x:10:14:Unix-to-Unix CoPy system:/etc/uucp:/bin/bash games:x:12:100:Games account:/var/games:/bin/bash man:x:13:62:Manual pages viewer:/var/cache/man:/bin/bash at:x:25:25:Batch jobs daemon:/var/spool/atjobs:/bin/bash wwwrun:x:30:8:WWW daemon apache:/var/lib/wwwrun:/bin/false ftp:x:40:49:FTP account:/srv/ftp:/bin/bash postfix:x:51:51:Postfix Daemon:/var/spool/postfix:/bin/false sshd:x:71:65:SSH daemon:/var/lib/sshd:/bin/false […]

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Operating Systems 12 Comments »
Feb
15

Short Message Center – Message Flows

Adnan Khurshid on February 15th, 2011

The function of short message center is to receive, store and schedule messages for delivery. There are mainly three network flows involved in the message receiving and delivery. They are as follows: 1) Mobile Origination 2) Mobile Termination 3) Alert Message Flow Lets analyze the flows one by one. 1) Mobile Origination Most of the […]

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Value Added Services 3 Comments »
Feb
11

How to login to ISQL*PLUS as sysdba in Oracle

Adnan Khurshid on February 11th, 2011

There are mainly 4 steps involved. 1) Create users for ISQL*PLUS DBA URL 2) Grant webdba role to those users 3) Restart the httpserver 4) Access the webpage @ http://localhost:port/isqlplus/dba Let’s follow these steps. 1) To create users, first you’ll have to define java_home and oracle_home and then run this weird long command to get […]

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Feb
11

How to change the port number for iSQL*PLUS in Oracle

Adnan Khurshid on February 11th, 2011

The default port to access iSQL*PLUS is 5560. You can access iSQL*PLUS with the following URL given that the oracle is installed on the local host ‘http://localhost:5560/isqlplus/’ To change the port number, modify the file “http-web-site.xml” as given below:

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Feb
10

How to retrieve command history in Linux/Unix servers

Adnan Khurshid on February 10th, 2011

The command history is stored in the file ‘bash_history’ which you can access as follows: linux:~ # less ~/.bash_history The file contains a list of all the commands which are stored in the buffer. You can also see these commands in sequence with the line numbers by using ‘history’ command. linux:~ # history The history […]

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Operating Systems 1 Comment »
Feb
6

How to sort files in Linux

Adnan Khurshid on February 6th, 2011

To display the files sorted in ascending order, we use the command ‘sort’. Suppose we have the following file and we want to sort out the data. linux:~ # more sort.txtBarrack ObamaGeorge BushBill ClintonRonald ReaganJimmy Carterlinux:~ # To sort the file we use the following command:

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Operating Systems 3 Comments »
Feb
6

How to add environment variables in Linux/Unix

Adnan Khurshid on February 6th, 2011

The environment variables are used by the shell and its child processes for normal execution of the programs. However, there are times when there is a need to add new variables for specific applications to work. First of all, check the environment parameters with ‘env’ command as shown below: To add the parameter simply use […]

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