March 16, 2010
Firewall – Reject or Drop a packet
Linux/Windows Support,Firewall – Reject or Drop a packet While setting up firewall rules, the biggest question that arises while blocking a packet is, whether to reject or drop that packet. Reject a packet – Block the packet with an error response to the sender of the packet. Drop a packet – Block the packet without any…
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March 16, 2010
HTTP Response Status Codes information
HTTP/WebServer,The HTTP status codes are divided into categories based on the first digit in the code Code Category Type Code Category Type 1nn Informational 2nn Success 3nn Redirection 4nn Client Error 5nn Server Error 1nn – Informational Codes 100 Continue 101 Switching Protocols 2nn - Success Codes 200 OK 201 Created 202 Accepted 203 Non-Authoritative…
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March 13, 2010
Difference between Buffer and Cache
Linux General,Buffers are allocated by various processes to use as input queues, etc. Most of the time, buffers are some processes’ output, and they are file buffers. A simplistic explanation of buffers is that they allow processes to temporarily store input in memory until the process can deal with it. Difference between Buffer and Cache Cache…
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March 13, 2010
Memory Usage in Linux
Linux General,Check the memory usage on a linux system with the command given below. The free command helps in getting the memory usage in the system [rams@stopprepare-lx ~]$ free -m total used free shared buffers cached Mem: 1002 985 17 0 93 380 -/+ buffers/cache: 512 490 Swap: 2055 0 2055 Total Memory in the system…
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March 13, 2010
Rendering MySQL query results in vertical format
Database,Easily reviewing SELECT query results in a shell window can be particularly difficult when a table consists of numerous columns. Remedying this inconvenience is easily done by appending the \G switch to the query: mysql>SELECT * from users WHERE id=1\G Executing this query with the \G switch attached formats the output like so: mysql test>select…
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March 13, 2010
Disable the Error Beep in MySQL
Linux General,To temporarily disable the beep, pass –no-beep along when logging into the server: %>mysql -u root -p –no-beep To permanently disable this annoyance, add no-beep to the [client] section of your .my.cnf file.
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March 13, 2010
How FreeBSD identifies hard disks and drives
Linux General,FreeBSD identifies various types of hard disks and drives with following naming convention ad ATAPI (IDE) disk da SCSI direct access disk acd ATAPI (IDE) CDROM cd SCSI CDROM fd Floppy disk To know the hardware detected by the kernel at boot time refer the file /var/run/dmesg.boot or use the command dmesg. The various hard…
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March 13, 2010
Create strong passwords in Unix
Linux/Windows Support,openssl command helps in creating strong passwords for user accounts, email addresses, web forms etc. openssl rand 12 -base64 The above command will create a random base 64 encoding string each time it’s run.
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March 13, 2010
Attach words horizontally using shell scripting
Linux General,To paste contents of two files horizontally, paste command can be used. Create a file called cmd with the following content: # cat cmd /usr/sbin/useradd /usr/sbin/useradd /usr/sbin/useradd Create another file called newusers # cat newusers tom dick harry Now run the following command # paste -d ” ” cmds newusers > add.sh The -d ”…
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March 13, 2010
Find empty files in Linux
Linux General,find command provides two options to detect empty files $ find . -size 0c or $ find . -empty To find and delete all the empty files under the current directory at one go $ find . empty -exec rm -f {} \; To find and delete all empty directories under the current directory $…
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