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

1D1C - size
by Dhanasekar 19 Feb '23

19 Feb '23

size - list section sizes and total size of binary files $ cat hello.c #include <stdio.h> int main() { // printf() displays the string inside quotation printf("Hello, World!"); return 0; } $ gcc hello.c -o hello.o $ size hello.o To display in octal $ size -o hello.o To display in hexadecimal $ size -x hello.o To display in system V format and hexadecimal values $ size -Ax hello.o regards, T.Dhanasekar

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1D1C - shutdown
by Dhanasekar 18 Feb '23

18 Feb '23

shutdown - is used to shutdown the system in a safe way syntax $ shutdown [OPTIONS] [TIME] [MESSAGE] To shutdown the system at a specified time 6 P.M $ sudo shutdown 18:00 To schedule a system shutdown in 30 minutes from now $ sudo shutdown +30 To shutdown the system immediately $ sudo shutdown now To shutdown the system in 30 minutes from now and notify the users with message “system upgrade” $ sudo shutdown +30 "system upgrade" To halt your system $ sudo shutdown -H To make shutdown power-off machine $ sudo shutdown -P To reboot using shutdown $ sudo shutdown -r To specify a time argument and a custom message $ sudo shutdown -r +10 "system upgrade" To cancel a scheduled shutdown $ sudo shutdown -c To cancel a scheduled shutdown, and to broadcast a message to all users $ sudo shutdown -c "reboot is cancelled" regards, T.Dhanasekar

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1D1C - showkey
by Dhanasekar 17 Feb '23

17 Feb '23

showkey - examine the codes sent by the keyboard To examine the codes sent by the keyboard $ sudo showkey To display print options $ sudo showkey -h To start showkey in scan code dump mode $ sudo showkey -s To start showkey in keycode dump mode $ sudo showkey -k To start showkey in `ascii‘ dump mode. $ sudo showkey -a regards, T.Dhanasekar

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1D1C - shuf
by Dhanasekar 16 Feb '23

16 Feb '23

shuf - writes a random permutation of the input lines to standard output shuf command without any option $ shuf 1 2 3 ctrl+d 3 1 2 $ cat file.txt msg1 msg2 msg3 msg4 msg5 msg6 To shuffle all the lines in the file $ shuf file.txt To add the number of lines to shuffle $ shuf -n 3 file.txt To make shuf as a range $ shuf -i 10-30 To get only one output from the randomized range $ shuf -i 10-100 -n 1 To shuffle a range and allow displaying three outputs which can be repetitive. $ shuf -i 10-100 -n 3 -r To use shuf as a List $ shuf -e a b c d $ shuf -e 1 2 3 4 To randomize a list and decide to only output two output lines $ shuf -e -n 2 1 2 3 4 $ shuf -e -n 2 a b c d To write output to a file $ shuf -i 10-20 -o file.txt $ cat file.txt regards, T.Dhanasekar

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1D1C - shred
by Dhanasekar 15 Feb '23

15 Feb '23

shred - overwrite a file to hide its contents, and optionally delete it syntax $ shred [filename] $ shred sample.txt To designate number of times to overwrite a file $ shred -n 2 example.txt To overwrite and delete a file $ shred -uv sample1.txt To selectively overwrite bytes of text $ shred -s [number_of_bytes] [filename] $ shred -s 10 password.txt To run shred with verbose mode $ shred -v file.txt To change permissions to allow writing if necessary $ shred -f [filename] $ shred -f file.txt To hide shredding from the file system. $ shred -z filename $ shred -z file.txt To Display shred Basic Details and Version and help options $ shred --version $ shred --help regards, T.Dhanasekar

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1D1C - shasum
by Dhanasekar 14 Feb '23

14 Feb '23

shasum - Print or Check SHA Checksums syntax $ shasum [OPTION]... [FILE]... $ cat sha_example.txt This is test message for shasum $ shasum sha_example.txt $ sha1sum sha_example.txt $ sha256sum sha_example.txt or $ shasum -a 256 sha_example.txt $ sha512sum sha_example.txt To generate the SHA value for text on the console $ sha256sum -t This is test message (Enter) Ctrl+d regards, T.Dhanasekar

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1D1C - shar
by Dhanasekar 13 Feb '23

13 Feb '23

shar - create a shell archive $ sudo apt install sharutils provides shar package To create a shar archive file. $ shar *.txt > mytext.shar $ shar *.pdf > mypdf.shar $ shar *.mp3 > mymp3.shar $ shar *.c > myc.shar remove all .txt , .pdf , .mp3 , .c files and then, To extract shar archive file $ unshar mytext.shar $ unshar mypdf.shar $ unshar mymp3.shar $ unshar myc.shar regards, T.Dhanasekar

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300 linux commands with examples cheat sheet
by Dhanasekar 12 Feb '23

12 Feb '23

Hi 300 linux commands with examples compiled from 1 Day 1 Command as long cheat sheet upload @ https://github.com/tkdhanasekar/linux_commands_examples/blob/main/linux_300… regards, T.Dhanasekar

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1D1C - sha1sum , sha256sum
by Dhanasekar 12 Feb '23

12 Feb '23

sha1sum - compute and check SHA1 message digest syntax $ sha1sum [OPTION] [FILE_NAME] To create the SHA-1 of a file $ sha1sum example.txt To create the SHA-256 of a file $ sha256sum example.txt To write the SHA-1 of a file to a file $ sha1sum example.txt > example.sha1 add some contents to example.txt and check with $ sha1sum -c example.sha1 example.txt: FAILED sha1sum: WARNING: 1 computed checksum did NOT match updated the SHA-1 file against the example.txt $ sha1sum new.txt > example.sha1 $ sha1sum -c example.sha1 example.txt: OK To forcefully change the command’s capabilities to read in binary mode $ sha1sum -b example.sha1 To print help commands $ sha1sum - -help To get a list of other sha-related commands $ sha regards, T.Dhanasekar

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1D1C - sh
by Dhanasekar 11 Feb '23

11 Feb '23

sh - is a command language interpreter that executes commands read from a command line string, the standard input, or a specified file. To Invoke the Bourne shell $ sh To run the bash script $ sh example.sh regards, T.Dhanasekar

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ILUG-D February 2023