May 2023 - ILUG-D - lists.fsci.in

1D1C - wc
by Dhanasekar 24 May '23

24 May '23

wc - print newline, word, and byte counts for each file syntax $ wc [options] filenames wc without options will display (number of lines), (number of words) and (number of bytes) of the file $ wc file.txt To Count Number of Lines $ wc -l file.txt To Display Number of Words $ wc -w file.txt To Count Number of Bytes and Characters $ wc -c file.txt $ wc -m file.txt To Display Length of Longest Line\ $ wc -L file.txt regards, T.Dhanasekar

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DebConf23 - Call for sponsors
by Sahil Dhiman 23 May '23

23 May '23

Hey folks, As many of you might already know, DebConf23 [1] is taking place in Kochi, Kerala this year from 10th to 17th September. This marks the first time in 23 years of DebConf history when DebConf is coming to India (and second time in Asia). For the conference, we're looking for potential Indian and foreign sponsors. If you or your organization use/benefit from Debian, this is a great opportunity to showcase and promote your organization to 350+ live attendees and many more viewing the conference online, while also supporting the development of Debian. Of course we have various associated perks and benefits [2]. List of already committed [3] and past year sponsors can be found here [3]. You can use this one page flyer [5] or detailed brochure [5] for starting internal discussions in your organization. Feel free to reach out to Praveen, me or sponsor(a)debconf.org (all in Cc) for any queries. [1]: https://debconf23.debconf.org/ [2]: https://debconf23.debconf.org/sponsors/become-a-sponsor/ [3]: https://debconf23.debconf.org/sponsors/ [4]; https://debconf22.debconf.org/sponsors/ [5]: https://media.debconf.org/dc23/fundraising/debconf23_sponsorship_flyer_en.p… [6]: https://media.debconf.org/dc23/fundraising/debconf23_sponsorship_brochure_e… Cheers! Sahil Dhiman, for DebConf23 fundraising team

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1D1C - watch
by Dhanasekar 23 May '23

23 May '23

watch - execute a program periodically, showing output fullscreen syntax $ watch [option] [command] To Run Command with a Custom Interval $ watch -n 5 free -h $ watch -n 3 date To highlight changes between updates $ watch -d [command] $ watch -d date $ watch -d free -h To exit if there is a change in the output $ watch -g [command] $ watch -g free To hide the watch Command Header $ watch -t date To alert on error $ watch -b [command] regards, T.Dhanasekar

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1D1C - wait
by Dhanasekar 22 May '23

22 May '23

wait - is a built-in command of Linux that waits for completing any running process. syntax $ wait [options] ID To wait for a background process with PID 7872 $ wait 7872 $ rsync -a /home/Documents /tmp/Documents & [1] 78724 $ wait %1 To make waits for any multiple background job to complete and return the job exit status $ wait -n <pid_1> <pid_2> <pid_3> wait command in shell scripts $ vim wait.sh #!/bin/bash sleep 20 & process_id=$! echo "PID: $process_id" wait $process_id echo "Exit status: $?" :x $ sh wait.sh regards, T.Dhanasekar

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1D1C - wall
by Dhanasekar 22 May '23

22 May '23

wall - is used to display a message on the terminals of all logged-in users. syntax $ wall [OPTIONS] [<FILE>|<MESSAGE>] To display a message on the terminals of all logged-in users $ wall "The system will be rebooted in 20 minutes." To suppress the banner and show only the text to the logged-in users $ wall -n "The system will be rebooted in 20 minutes." To write multi-line messages $ wall To pipe the output of another command to wall $ echo "The system will be rebooted in 20 minutes. \nPlease save your work." | wall To broadcast a message from a file $ wall message_from_file.txt To broadcast a message to a group $ wall -g devops "The system will be rebooted in 20 minutes." regards, T.Dhanasekar

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1D1C - vmstat
by Dhanasekar 20 May '23

20 May '23

vmstat - Report virtual memory statistics syntax: $ vmstat [options][delay [count]] To run vmstat without options $ vmstat To Display Active and Inactive System Memory $ vmstat -a To display about memory, event counters, and CPU scheduling statistics $ vmstat -s To display number of forks since boot $ vmstat -f To display Quick Summary Disk Statistics $ vmstat -D To Display Disk Statistics $ vmstat -d To Display Partition Statistics $ vmstat -p vda1 To Display Timestamp Information for Updates $ vmstat -t To use a Delay Value $ vmstat [delay] $ vmstat 4 To use a Count Value $ vmstat [delay[count]] $ vmstat 4 5 To Change Units $ vmstat 3 -S M To Display Statistics for Slabs $ sudo vmstat -m regards, T.Dhanasekar

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1D1C - virsh
by Dhanasekar 19 May '23

19 May '23

Virsh - is a management user interface for virsh guest domains To list a KVM vm guest $ virsh list $ virsh list --all $ virsh list --inactive $ virsh list --uuid $ virsh list --name $ virsh list --state-running $ virsh list --state-paused $ virsh list --persistent $ virsh list --with-snapshot $ virsh list --autostart $ virsh list --help To Check Node info $ virsh nodeinfo To Check Domain Error $ virsh domblkerror <vm_name> To check a domain information $ virsh dominfo <vm_name> To Check Node CPU Stats $ virsh nodecpustats To Check Node Memory Stats $ virsh nodememstats To Check Node hostname $ virsh hostname To start vm $ virsh start <vm_name> To set a vm to start automatically on system startup $ virsh autostart <vm_name> To disable autostart $ virsh autostart --disable <vm_name> To shutdown a running vm $ virsh shutdown <vm_name> To make forceful shutdown of vm $ virsh destroy <vm_name> To restart a vm $ virsh reboot <vm_name> To suspend a vm $ virsh suspend <vm_name> To restore a suspended vm $ virsh resume <vm_name> To save the current state of a vm $ virsh save vm_name vm_name.save To restore saved vm from the file $ virsh restore vm_name.save To create a 3GB volume named vol2 on the default storage pool $ virsh vol-create-as default vol2.qcow2 3G To List volumes $ virsh vol-list --pool default $ virsh vol-list --pool images To attach created volume $ virsh attach-disk --domain <vm_name> \ --source /var/lib/libvirt/images/vol2.qcow2 \ --persistent --target vdb To detach volume $ virsh detach-disk --domain <vm_name> --persistent --live --target vdb To List storage pools $ virsh pool-list To delete volume $ sudo virsh vol-delete vol2.qcow2 --pool default To create a snapshot $ virsh snapshot-create-as \ --domain <vm_name> \ --name "vm_snapshot1" \ --description "vm_name snapshot 1-working" To list available snapshots $ virsh snapshot-list <vm_name> To display info about a snapshot $ virsh snapshot-info --domain <vm_name> --snapshotname vm_snapshot1 To revert the snapshot $ virsh snapshot-revert --domain <vm_name> --snapshotname vm_snapshot1 --running To delete snapshot $ virsh snapshot-delete --domain <vm_name> --snapshotname vm_snapshot1 To clone a vm $ virt-clone --connect qemu:///system \ --original vm_name \ --name vm_name_clone \ --file /var/lib/libvirt/images/vm_name_clone.qcow2 To manage VM vcpus $ virsh setvcpus --domain vm_name --maximum 2 --config $ virsh setvcpus --domain vm_name --count 2 --config To manage VM memory $ virsh setmaxmem <vm_name> 2048 --config $ virsh setmem <vm_name> 2048 --config regards, T.Dhanasekar

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1D1C - vlc
by Dhanasekar 18 May '23

18 May '23

vlc - it is used to play vlc from command line To open vlc from terminal $ vlc & $ vlc /path/to/file.mp3 To play all the files $ vlc -Z * To read in shuffle mode $ vlc -L [files] To repeat the playlist $ vlc -R [files] To Put Video in Full Screen $ vlc --fullscreen [file] regards, T.Dhanasekar

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1D1C - w
by Dhanasekar 17 May '23

17 May '23

w - Show who is logged on and what they are doing syntax $ w [options] [username] w command without options $ w To Display the Short Format $ w -s To List the w Command Output Without Printing the Header $ w -h To ignore usernames when calculating the current process and CPU times $ w -u To Display the IP Address $ w -i To Display in Old Style $ w -o To show remote hostname field $ w -f To print help options $ w --help regards, T.Dhanasekar

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1D1C - virt-install
by Dhanasekar 16 May '23

16 May '23

virt-install - provision new virtual machines To define a name of the VM $ sudo virt-install --name ubuntu20.04 To define CPU for the VM $ sudo virt-install --name ubuntu20.04 --vcpus 2 To define memory for the VM $ sudo virt-install --name ubuntu20.04 --memory 20480 To define OS Variant and OS Type $ sudo virt-install --name ubuntu20.04 --memory 20480 --vcpus=2 --os-type=Linux --os-variant=ubuntu20.04 To assign this default network for VM $ sudo virt-install --name ubuntu20.04 --memory 20480 --vcpus=2 --os-type=Linux --os-variant=ubuntu20.04 \ --location=/tmp/ubuntu20.04.iso --network network=default --graphics=vnc -v regards, T.Dhanasekar

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