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

1D1C - truncate
by Dhanasekar 12 Apr '23

12 Apr '23

truncate - shrink or extend the size of a file to the specified size To Clear contents of a file with truncate $ truncate -s 0 example.txt To truncate a file to a specific size $ truncate -s 200K example.txt To extend file size $ truncate -s +400K example.txt To reduce file size $ truncate -s -100k example.txt regards, T.Dhanasekar

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1D1C - troff
by Dhanasekar 11 Apr '23

11 Apr '23

troff - it performs typesetting functions and formats documents Troff the input file $ troff example.txt troff command $ troff Hello world! ^D To pipe the output of troff $ troff > output Welcome to Linux world ^D To append the output of troff $ troff >> output Welcome to python ^D regards, T.Dhanasekar

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1D1C - trap
by Dhanasekar 10 Apr '23

10 Apr '23

trap - is used to execute a command when the shell receives any signal is called `trap`. syntax $ trap [options] "[arguments]" [signals] To display the list of all commands associated with each condition $ trap To display the list of all signal names with number $ trap -l To Set `trap` command with signal number of SIGUP, SIGQUIT and SIGKILL $ trap 'echo Trap command executed' 1 3 9 $ press Ctrl+C $ ^CTrap command executed $ trap To Set trap command for ERR and EXIT $ trap 'rm file.txt' err exit $ trap regards, T.Dhanasekar

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1D1C - traceroute
by Dhanasekar 09 Apr '23

09 Apr '23

traceroute - traces path to a network host To find the network path from my machine to google.com $ traceroute google.com To Disable IP address and host name mapping $ traceroute google.com -n $ traceroute ilugc.in -n To Configure Response Wait Time $ traceroute google.com -w 0.1 To configure number of queries per hop $ traceroute google.com -q 5 To Configure the TTL value to start with $ traceroute google.com -f 8 $ traceroute ilugc.in -f 10 regards, T.Dhanasekar

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1D1C - tr
by Dhanasekar 08 Apr '23

08 Apr '23

tr - is used to translate and/or delete characters from stdin input and writes to stdout $ cat example.txt linux os is powerful linux os is versatile linux os is best To change all lowercase letters in the text to uppercase and vice versa $ cat example.txt | tr [:lower:] [:upper:] or $ cat example.txt | tr [a-z] [A-Z] To save the results written to stdout in a file $ cat example.txt | tr [a-z] [A-Z] >output.txt To send input to tr using the input redirection and redirect the output to a file $ tr [a-z] [A-Z] < linux.txt >output.txt To delete characters and remove spaces $ cat domain.txt www. ilugc. in www. chennaipy. org www. google. com $ cat domains.txt | tr -d '' To remove repeated characters in a sequence $ cat domains.txt www. ilugc........... innnn www. chennaipy. org www. google. com $ cat domains.txt | tr -s '' To delete all the letters and only leave the UID $ echo "My UID is $UID" | tr -cd "[:digit:]\n" To break a single line of words (sentence) into multiple lines $ echo "My UID is $UID" $ echo "My UID is $UID" | tr " " "\n" To translate multiple lines of words into a single sentence $ cat uid.txt My UID is 1000 $ tr "\n" " " < uid.txt To translate single character, for instance, a space into a “ : ” $ echo "ilugc.in =>linux,devops,cloud,programming" | tr " " ":" $ echo "ilugc.in =>linux devops cloud programming" | tr " " ":" regards, T.Dhanasekar

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1D1C - tput
by Dhanasekar 07 Apr '23

07 Apr '23

tput - is used to query the terminfo terminal database and check if that terminal supports a specific feature. To Set the Cursor Position using tput cup $ tput cup 5 6 $ tput cup 10 10 To Clear the Screen Using tput clear $ tput clear To Get the Number of Columns and Lines of a Terminal $ tput cols $ tput lines To Execute Multiple tput Commands $ tput -S <<END > clear > cup 2 4 > END To Turn On and Turn Off Highlighting $ echo `tput bold`ilugc`tput sgr0` $ echo `tput sgr0`ilugc`tput sgr0` To Underline Text using smul and rmul $ echo `tput smul`ilugc`tput rmul` $ echo `tput rmul`ilugc`tput rmul` To Hide and Unhide the Cursor using civis and cnorm $ tput civis $ tput cnorm regards, T.Dhanasekar

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JOB | On Premises DevOps Automation Engineer (London/Singapore)
by James Tobin 06 Apr '23

06 Apr '23

Hello, I'm working with an employer that is looking to hire someone to join their global on premises devops automation team. You should have experience in automation and management of platform configuration. They are looking at using Kubernetes or similar for their on premises servers and processes; moving away from virtual machines. You should be articulate and confident in all things ansible and automation; capable of taking center stage in meetings, presentations and tech conferences. The position will be based in London and/or Singapore. I had hoped that some members of this group may like to discuss further. I can be reached using "JamesBTobin (at) Gmail (dot) Com". Kind regards, James

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1D1C - tload
by Dhanasekar 06 Apr '23

06 Apr '23

tload - graphic representation of system load average syntax $ tload [options] [terminal] To display the representation of the average system load as a graph on the terminal $ tload To set delay between graph update in seconds $ tload -d 2 To change the scale of the graph $ tload -s 10 To print a graph of the current system load average to a specified tty $ tload -d 2 -s 10 /dev/tty3 To run tload over the ssh based session $ ssh -t user1(a)192.168.122.100 tload -d 2 regards, T.Dhanasekar

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1D1C - touch
by Dhanasekar 05 Apr '23

05 Apr '23

touch - change file timestamps To Create an Empty File $ touch file.txt To Create Multiple Files $ touch file1.txt file2.txt file3.txt file4.txt To Change File Access and Modification Time $ touch -a file.txt To Set File Timestamp Using Date String $ touch -d tomorrow demo To Avoid Creating New File $ touch -c file.txt To Change File Modification Time $ touch -m sample.txt To Explicitly Set the Access and Modification times $ touch -c -t YYDDHHMM sample.txt To Use the time stamp of example.txt to sample.txt $ touch -r sample.txt example.txt To Create a File using a specified time $ touch -t YYMMDDHHMM.SS demofile $ touch -t 2211260600.26 demofile regards, T.Dhanasekar

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1D1C - timeout
by Dhanasekar 04 Apr '23

04 Apr '23

timeout - run a command with a time limit syntax $ timeout [OPTION] DURATION COMMAND [ARG]... To specify timeout value (in seconds) with the command $ timeout 5 ping ilugc.in $ timeout 5h ping ilugc.in $ timeout 5d ping ilugc.in $ timeout 8 tail -f /var/log/syslog we can specify time in seconds , minutes , hours and days To make Preserve status returns an exit status even the process is terminated forcefully $ timeout --preserve-status 2m ping facebook.com Ctrl+c $ Ctrl+c $ echo $? To set a signal to the command $ timeout -s <command> To check the available signals $ kill -l $ sudo timeout -s SIGKILL ping ilugc.in To send signals by using a signal number $ sudo timeout -s 9 ping ilugc.in To kill the timeout command after 5 seconds if the connection is not established $ sudo timeout -k 5 1m ping google.com regards, T.Dhanasekar

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ILUG-D April 2023