How to get the Serial number of the Mellanox card.

lspci -xxxxvvvv | grep -E "Serial number|Mellanox"

Linux LVM overview.

How to see specific information about disk

hdparm -i /dev/sda smartctl -A /dev/sda hdparm -tT /dev/sda used to Do a read speed test on disk sda badblocks -s /dev/sda used to Test for unreadable blocks on disk sda

How to check the tcp udp and network sockts in linux

netstat -ntlp to view the open TCP sockets netstat -nulp to view the open UDP sockets netstat -nxlp to view the open Unix sockets

How to find the hidden files in Linux

du -sh .[!.]* *

How to check which shells are already installed and configured on our machine ?

by using the chsh -l [user@localhost ~]$ chsh -l /bin/sh /bin/bash /sbin/nologin /usr/bin/sh /usr/bin/bash /usr/sbin/nologin /usr/bin/fish Or by using cat /etc/shells we can change the following default shell using chsh -s /usr/bin/bash Now all that is left to do is preform a logoff-logon cycle, and enjoy our new default shell.

How to Shows all bad login attempts into the system

Try with the following command lastb

How to mount the nfs share in all the hosts.

--- - name: Mount the NFS share hosts: all become: true vars: mynfs: "172.2.0.200:/nfs/data" mountpoint: "/share" permission: '0777' myopts: 'rw,sync' tasks: - name: utility present redhat-like ansible.builtin.yum: name: - nfs-utils - nfs4-acl-tools state: present when: ansible_os_family == 'RedHat' - name: utility present debian-like ansible.builtin.apt: name: - nfs-common - nfs4-acl-tools state: present when: ansible_os_family == 'Debian' - name: check mountpoint exist ansible.builtin.file: path: "{{ mountpoint }}" state: directory mode: "{{ permission }}" owner: root group: root - name: mount network share ansible.posix.mount: src: "{{ mynfs }}" path: "{{ mountpoint }}" fstype: nfs opts: "{{ myopts }}" state: mounted

How to restart the ssh service in all the hosts.

--- - name: restart ssh service in all the hosts. hosts: all become: true tasks: - name: sshd restart ansible.builtin.service: name: sshd state: restarted enabled: true

How to restrict a user a login @ specefic time in Linux

Use the pam_time module in the Pluggable Authentication Modules (PAM) system to restrict login times. Edit the /etc/security/time.conf file to specify time restrictions. You can define rules for specific users or groups. Edit the /etc/security/time.conf login ; * ; !gurudatta ; Wk0630-1500 This line denies login for all users except "user1" from Monday to Friday between 6:30 AM to 15:00 PM. Ensure that the pam_time module is enabled and configured properly in the PAM configuration files (/etc/pam.d/).

How to start the cell nodes in Exadata

for host in `cat cell_group`; do echo ${host}: `ipmitool -H ${host}-ilom -U root -P welcome1 chassis power on` done

The maximum file size in Linux depends on the file system being used

The maximum file size in Linux depends on the file system being used. Here are the maximum file size limits for some common Linux file systems: ext2/ext3: Maximum file size is 2TB. ext4: Maximum file size is 16TB with 4KB blocks and 50TB with 64KB blocks. XFS: Maximum file size is 8 exbibytes (EiB). Btrfs: Maximum file size is 16 exbibytes (EiB). ReiserFS: Maximum file size is 8TB. ZFS: Theoretical maximum file size is 16 exbibytes (EiB) but practically limited by the size of the pool.

How to remove Orphan Packages in Linux

yum autoremove in RHEL based Linux apt-get autoremove in Debain based Linux

Pxe

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