The Ask I have run a command in an ssh session and would like to keep it running even upon exit from ssh session. Is there any way to prevent termination of process upon exit from session running that process? The Answer There are 2 ways to do this : nohup - To run a new process that can run in background even after closing the terminal. disown - Can be used when the process is already running and you have not used nohup to run it. Lets take a simple example of a long running … [Read more...] about How to keep a process running after killing the terminal in Linux
Archives for November 2018
How to create restricted korn shell in CentOS/RHEL
rksh (restricted korn shell) is the restricted version of ksh (the Korn shell), used in secure environments. rksh prevents you from changing out of the directory or from redirecting output. Latest ksh package in RHEL7 installs a symlink to /bin/ksh93 named rksh, that acts as described in the ksh manual page. For RHEL6, execute the below command: # ln -sf /bin/ksh93 /bin/rksh For bash it would be: # ln -sf /bin/bash /bin/rbash Notes - Make the login shell of the user point to … [Read more...] about How to create restricted korn shell in CentOS/RHEL
“kernel: statd: server localhost not responding, timed out” Messages in /var/log/messages
The Problem The following messages appear in /var/log/messages: Dec 16 07:43:45 kernel: statd: server localhost not responding, timed out Dec 16 07:43:45 kernel: lockd: cannot monitor [IP] Dec 16 07:43:45 kernel: lockd: failed to monitor [IP] Dec 16 08:35:15 kernel: statd: server localhost not responding, timed out Dec 16 08:35:15 kernel: lockd: cannot monitor [IP] Dec 16 08:35:15 kernel: lockd: failed to monitor [IP] Dec 16 08:47:20 kernel: statd: server localhost not … [Read more...] about “kernel: statd: server localhost not responding, timed out” Messages in /var/log/messages
Difference between using srvctl vs using sqlplus for start/stop one or more Oracle Database Instances
The Problem We have had some instances where it seemed that starting rac databases through sqlplus caused performance issues (high load on database server ). Restarting the nodes using srvctl seemed to resolve the performance issue. "Is there any difference between using srvctl vs using sqlplus for starting or stopping one or more database nodes."? The Solution The Differences between SQLPLUS and SRVCTL There are some differences between the use of SQLPLUS and SRVCTL utilities. - Both … [Read more...] about Difference between using srvctl vs using sqlplus for start/stop one or more Oracle Database Instances
How to create the chroot from Rescue Mode in CentOS/RHEL
The Ask When booted into Rescue Mode, I chose Skip to not build the root filesystem, how do I make it again without rebooting? The Answer 1. Get to the Rescue Mode shell: sh-3.2# 2. Ensure a directory exists to hold the root filesystem: # mkdir -p /mnt/sysimage/ 3. Find the /boot/ partition: # fdisk -l We will use the example /dev/sda1 4. Find the root storage: # lvm pvscan # lvm vgscan # lvm lvscan We will use the example: /dev/mapper/vg-lv 5. Mount the root … [Read more...] about How to create the chroot from Rescue Mode in CentOS/RHEL
How To Change Timezone for Oracle Grid Infrastructure
This post illustrates how to change timezone setting for Grid Infrastructure after installation. Note: To check the current time zone on Linux, use the command: "timedatectl | grep 'Time zone'" To check the current time zone on Windows, use the command: "systeminfo | findstr /C:"Time Zone"" Grid Time Zone Setting Once OS default timezone is changed, make sure: For 11.2.0.1, shell environment variable TZ is set correctly for grid user and root. For 11.2.0.2 and above, TZ entry in … [Read more...] about How To Change Timezone for Oracle Grid Infrastructure
How to Set the TimeZone in Solaris 10,11
The Ask In Solaris Operating System (OS), where is the default timezone set, and how can it be changed? Solaris 11 OS and above 1. The default timezone is defined as a property of the "svc:/system/timezone:default" SMF service: # svcs timezone STATE STIME FMRI online Aug_22 svc:/system/timezone:default # svcprop timezone:default |grep localtime timezone/localtime astring US/Eastern 2. To change the default timezone, use the svccfg and then refresh the service … [Read more...] about How to Set the TimeZone in Solaris 10,11
Cannot Increase “nproc” Value More Than 1024 in CentOS/RHEL 6
The Problem "/etc/security/limits.conf" is updated with the following and the server is rebooted: # vi /etc/security/limits.conf * - nproc 16384 However, "ulimit -a" (for root & all users) still shows the 1024 for "max user processes" instead of 16384: # ulimit -a ... max user processes (-u) 1024 ... The Solution CentOS/RHEL 6 has another file for setting the nproc value - /etc/security/limits.d/90-nproc.conf # cat /etc/security/limits.d/90-nproc.conf * soft … [Read more...] about Cannot Increase “nproc” Value More Than 1024 in CentOS/RHEL 6
How to Write a “rc script” to stop a service, before the network is shut down in CentOS/RHEL 6
The Ask The need is to cleanly shutdown a service but before the network is down using the rc scripts in CentOS/RHEL 6 system. The Answer The solution is to add a "SystemV rc" script that only creates the lock file at start and stops the application at stop. 1. For this, create the file /etc/rc.d/init.d/appshutdown with the following content: #!/bin/sh # # appshutdown after network shutdown # # chkconfig: 2345 00 00 # description: This is a script to stop jboss # # processname: … [Read more...] about How to Write a “rc script” to stop a service, before the network is shut down in CentOS/RHEL 6
How to Execute Scripts/Commands using /etc/rc.d/rc.local in CentOS/RHEL 7
The Problem The scripts/commands in the configuration file /etc/rc.d/rc.local could not work at boot time in a CentOS/RHEL 7 system. Same used to work in earlier CentOS/RHEL versions. Is it depricated or is there a workaround to still use this method? The Answer The rc.local service is stopped by default in CentOS/RHEL 7. If you check the etc/rc.d/rc.local configuration file, there are hints about this. # cat /etc/rc.d/rc.local #!/bin/bash # THIS FILE IS ADDED FOR COMPATIBILITY … [Read more...] about How to Execute Scripts/Commands using /etc/rc.d/rc.local in CentOS/RHEL 7