All I/O, including files, pipes, and sockets, are handled by the kernel via a mechanism called the file descriptor. A file descriptor is a small unsigned integer, an index into a file-descriptor table maintained by the kernel and used by the kernel to reference open files and I/O streams. Each process inherits its own file-descriptor … Continue reading File descriptors
The diff command mohammedrafi@NOC-RAFI:~$ vim file1 I go for shopping on Saturday I rest completely on Sunday I use Facebook & Tweeter for social networking mohammedrafi@NOC-RAFI:~$ vim file2 Today is Monday. I go for shopping on Saturday I rest completely on Sunday I use Facebook & Tweeter for social networking mohammedrafi@NOC-RAFI:~$ diff file1 file2 0a1 … Continue reading diff,cut,head,tail,more,less,paste,join,uniq,comm,tr,sort,
cron command is used to schedule the task daily at the same time repeatedly. "at" command is used to schedule the task only once i.e to run only one time. cron can be edited at cannot be edited, after its schedule. mohammedrafi@NOC-RAFI:~$ at 21:22 warning: commands will be executed using /bin/sh at> echo "this is … Continue reading Diffrence b/w at and cron
Introducing process basics A running instance of a program is called as process. A program stored in the hard disk or pen drive is not a process. When that stored program starts executing, then we say that process has been created and is running. Let's very briefly understand the Linux operating system boot-up sequence: 1. In … Continue reading Introducing process basics
Before Learning shell-script we need to know few prerequisite lets know them first things first https://shaikmdrafi.wordpress.com/2016/04/28/shell-scripts/ Comparison of shells Initially, the UNIX OS used a shell program called Bourne Shell. Then eventually, many more shell programs were developed for different flavors of UNIX. The following is brief information about different shells: •Sh—Bourne Shell •Csh—C Shell •Ksh—Korn … Continue reading shell-scripting deep dive
AWS SDK Boto Configuration 1) If you're executing code against AWS on an EC2 instance that is assigned an IAM role, which of the following is a true statement? The code will assume the same permissions as the EC2 role 2) An IAM role, when assigned to an EC2 instance, will allow code to be … Continue reading AWS Certified Developer – Associate Level
To list all kernel parameters [root@instance-1 ~]# sysctl -a abi.vsyscall32 = 1 crypto.fips_enabled = 0 debug.exception-trace = 1 debug.kprobes-optimization = 1 dev.hpet.max-user-freq = 64 dev.mac_hid.mouse_button2_keycode = 97 dev.mac_hid.mouse_button3_keycode = 100 ex: [root@instance-1 ~]# cat /proc/sys/fs/file-max 373992 [root@instance-1 ~]# sysctl -a |grep fs.file-max fs.file-max = 373992 [root@instance-1 ~]# sysctl -w fs.file-max=380000 fs.file-max = 380000 [root@instance-1 ~]# … Continue reading Managing kernel parameters
####################################################################### Exercise: Install a Jenkins Master and Prerequisites NOTE: Be sure you are using the same server version and distribution from the course for these topics. Basic Instructions Download the appropriate java jdk version from the Oracle website. For this course we use jdk-8u121. Copy the package from your local environment to the target server. … Continue reading jenkins (CJE) Exercise Guide
[root@mypc ~]# egrep ^menuentry /etc/grub2.cfg | cut -f 2 -d \' CentOS Linux (3.10.0-514.6.1.el7.x86_64) 7 (Core) CentOS Linux (3.10.0-123.4.2.el7.x86_64) 7 (Core) CentOS Linux, with Linux 3.10.0-123.el7.x86_64 CentOS Linux, with Linux 0-rescue-11264912be38456483e63dfd21d402f4 [root@mypc ~]# yum update |grep kernel-tools ---> Package kernel-tools.x86_64 0:3.10.0-514.6.1.el7 will be updated ---> Package kernel-tools.x86_64 0:3.10.0-514.21.1.el7 will be an update ---> Package kernel-tools-libs.x86_64 0:3.10.0-514.6.1.el7 … Continue reading Upgrading kernel version
ctrl+a to come to start of line in terminal ctrl+b to move backward one character ctrl+c to terminate process crtl+d to terminate session ctrl+e to come to end of line in terminal ctrl+f to move forward by one character ctrl+h to erase one character to your left of cursor ctrl+k to remove the character after … Continue reading Terminal short cuts
