Archives for April 2022

By default, each process running on the Linux system has its own private memory pages. One process cannot access memory pages being used by another process. The kernel maintains its own memory areas. For security purposes, no processes can access memory used by the kernel processes. To facilitate data sharing, you can create shared memory […]

join command joins lines of two files on a common field. Syntax: # join [OPTION]… FILE1 FILE2 For each pair of input lines with identical join fields, write a line to standard output. The default join field is the first, delimited by whitespace. When FILE1 or FILE2 (not both) is -, read standard input. join […]

It’s also possible to send signals to multiple processes matching a specified program or username by using the killall command. Here is the syntax: # killall [-u user] [-signal] name… To demonstrate, we will start a couple of instances of the sleep program and then terminate them. $ sleep 500 & [1] 18801 $ sleep […]

lastlog command prints the last login times for system accounts. Login information is read from the file /var/log/lastlog. lastlog Command OPtions Option Description -t n Print only logins more recent than n days ago. -u name Print only login information for user name. lastlog Command Examples 1. To print the last login of all the […]

lnstat command is offered by the iproute2 package. It provides unified Linux network statistics. lnstat Command Examples 1. To get the unified network statistics: # lnstat 2. To print the number of intervals: # lnstat -c 10 3. To dump list of available files/keys: # lnstat -d # lnstat –dump 4. To get the stats […]

locale command can be used to get the locale-specific information. This command has very few options to be used with. Run the locale command as the user to check the current locale. For example: # locale LANG=en_US.utf8 LC_CTYPE=”en_US.utf8″ LC_NUMERIC=”en_US.utf8″ LC_TIME=”en_US.utf8″ LC_COLLATE=”en_US.utf8″ LC_MONETARY=”en_US.utf8″ LC_MESSAGES=”en_US.utf8″ LC_PAPER=”en_US.utf8″ LC_NAME=”en_US.utf8″ LC_ADDRESS=”en_US.utf8″ LC_TELEPHONE=”en_US.utf8″ LC_MEASUREMENT=”en_US.utf8″ LC_IDENTIFICATION=”en_US.utf8″ LC_ALL= To change the locale to […]

The login utility logs users (and pseudo-users) into the computer system. If no user is specified, or if a user is specified and authentication of the user fails, login prompts for a user name. Authentication of users is configurable via pam. Password authentication is the default. If the file /etc/nologin exists, login displays its contents […]

logname command prints the user’s login name. For example: $ logname geek logname Comman Options Option Description –help display this help and exit –version output version information and exit 1. To print the users login name: # logname 2. To get the help for logname command: # logname –help 3. To output version information: # […]

Log files keep track of events on the system. They are essential for debugging problems and monitoring live machines. Log files grow as time passes and more events are recorded. Since the older data is less useful than the current data, log files are renamed when they reach a size limit and the oldest files […]

The minor version of RHEL server is defined by the /etc/redhat-release file and it belongs to redhat-release-server package. The lsb_release script points to /etc/redhat-release which gives the same output as ‘cat /etc/redhat-release’. Linux Standard Base (LSB) is basically a standard that multiple distributions sign up to. It specifies a Filesystem Hierarchy Standard (FHS), as well […]