LinuxAdmin

Linux System Admin

System tools for fedora/red hat:

• DNS = system-config-bind
• HTTP = system-config-httpd
• NFS = system-config-nfs
• Root password = system-config-rootpassword
• Samba NFS = system-config-samba
• Services = system-config-services
• Authentication = authconfig-gtk
• Date & Time = system-config-date
• Firewall = system-config-firewall
• Language = system-config-language
• Printing = system-config-printer
• SELinux Management = policycoreutils-gui
• Users & Groups = system-config-users
• Configuration Editor = gconf-editor
• Disk Usage Analyzer = gnome-utils
• Disk Utility = gnome-disks
• Kickstart = system-config-kickstart

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Enable service to run on boot:

• sudo systemctl enable <service>
  • eg: sudo systemctl enable bluetooth.service

Linux Processes

• Show running processes: ps
• Show processes for all users: ps aux
• Display running processes: top
• List processes via config directory (services started at boot via script in this directory ): ls /etc/init.d or ls /etc/rc.d
• list all processes with specific columns ( use -o parameter ): ps -e -o %mem,pid,uid,comm
• Sort output of ps by cpu usage: ps -e --sort=%cpu

Get all processes:

• ps -e

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Search for specific process:

• ps -e | grep <processname>

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Kill process:

• kill <processID>

Enable SSH

Install the ssh client if not already installed:

• sudo apt install openssh-client

If you want to enable SSH on Ubuntu server, use the following command:

• sudo apt install openssh-server

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If ssh in not being allowed remotely you will need to open port 22 on the firewall:

• sudo ufw allow 22

Linux Disk Space / Usage

Use the "df" command to see the disks mounted to the system

Can use df -BM to display output in blocksize megabytes or -h to output in human readable format

Use -T to disply the type of file system the mounted disk is

Use -x to exclude a type of file system eg

• df -x squashfs --total

Use -t to only include a type of filesystem eg

• df -t ext4

You can specify report of specific named file systems eg:

• df -h --total /dev /run

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Use "du" command to show folder disk usage eg:

• du
• du -BM
• du -h

Sort output by largest to smallest size

• du -sm | sort -nr

Use du to find biggest files and sort the output:

• sudo du -a | sort -n -r | head -n 20