Use the du command to list firectories with largest disk space. Replace DIREC in the following commands with a starting directory (e.g; / or /etc) # du -sh $DIREC/* | sort -r --human-numeric-sort | head -n10 In the above command, head -n10 option can be changed to list few or more results in the output. …
Are all numeric usernames allowed in AlmaLinux 8
All numeric login names are not supported in AlmaLinux and CentOS. usernames that begin with a digit and also contain letters are not known to have any issue. However, in CentOS 7 version, some system tools can make varying assumptions. In Almalinux 8 and future releases, ALL numeric usernames are not supported. For more details …
How to disable delayed ACKs
TCP throughput (SCP) from a remote host is slow. By looking at the trace, it is noticed that the CentOS server is waiting for up to 40ms before sending an ACK. In CentOS releases before 7.2, delayed Acks can only be reduced by cannot be eliminated. In CentOS 7.2, quickacks are tunable on a per …
How to check if FANOTIFY is enabled in Kernel
You can verify if the FANOTIFY is enabled in the kernel by using the following command. # cat /boot/config-$(uname -r) | grep FANOTIFYCONFIG_FANOTIFY=yCONFIG_FANOTIFY_ACCESS_PERMISSIONS=y FANOTIFY is built in the kernel, so there is no need to load other modules. It is enabled by default in CentOS 7,8 and AlmaLinux 8.
How to calculate free space in thin pool LV
You can calculate free space in thinpool LVM by using the following command: # dmsetup status[... ]vg1-poolB-tpool: 0 45135824 thin-pool 1 4773/178944 90879/206109 - rw discard_passdown queue_if_no_space - 1024 In the above output, 206109 are the total available extents and 90879 are the free extents. You can now find the chunk size as follows: # …
How many simultaneous VNC sessions can run on a Linux server
VNC is one of the most common methods to access servers remotely by multiple users simultaneously. VNC is usually configured as a systems service that is always on, serving a GUI session for a single or multiple users simultaneously. There is no limit on the number of VNC sessions in a Linux-based server, but constraints …
How to start failed VNC service
The VNC server is configured on a Linux machine, but the service status is shown as failed. systemctl status vncserver@:1.service ● vncserver@:1.service - Remote desktop service (VNC) Loaded: loaded (/etc/systemd/system/vncserver@:1.service; enabled; vendor preset: disabled) Active: failed (Result: exit-code) since Mon 2021-09-01 11:30:03 +04; 11s ago Process: 13739 ExecStart=/usr/sbin/runuser -l vncuser -c /usr/bin/vncserver %i (code=exited, status=1/FAILURE) …
How to restrict normal user to run only limited set of commands
Normal users in Linux are usually given permission to execute a certain command in /bin/ and /usr/local/bin. Follow the below steps to remove those permissions and restrict users to run only specific commands. Enter the following command to generate a restricted shell. cp /bin/bash /bin/rbash Change the shell as a restricted shell while adding the …
How to configure VNC server in AlmaLinux 8.3
Install the required VNC server packages in AlmaLinux 8.3 as follows: yum -y install tigervnc-server tigervnc The default configuration files for the tigervnc-server are located in /etc/tigervnc. In this directory, the following files are present. vncserver.usersvncserver-config-mandatoryvncserver-config-defaults Map the users to a particular port by adding the following option (:x=user) in /etc/tigervnc/vncserver.users file. :1=vnc-user1:2=vnc-users2 You should …
How to set interface to promiscuous mode permanently
You can use a script to apply promiscuous settings to an interface or multiple interfaces when they come online. touch /etc/NetworkManager/dispatcher.d/30-promiscchmod +x /etc/NetworkManager/dispatcher.d/30-promisc Add following script code to 30-promisc file. #!/bin/bashif [ "$1" == "eth0" ] && [ "$2" == "up" ]; thenip link set dev "$1" promisc onfi You can also use network initscripts …