ILUG-D February 2023

ilugd@lists.linuxdelhi.org

4 participants
28 discussions

1D1C - set
by Dhanasekar 05 Feb '23

05 Feb '23

set - is a built-in Linux shell command that displays and sets the names and values of shell and Linux environment variables syntax $ set [options] [arguments] To list all settings $ set $ set debian redhat arch To list all the parameters in the order of $1 $2 $3 $ echo "$*" $ echo $1 $ echo $2 $ echo $3 To unset All Positional Parameters $ set -- To print out an error on the shell if the script runs into an undefined variable $ vim example1.sh #!/bin/bash set -u echo $foo echo "welcome to ilugc" :x $ bash example.sh To display an Error If a Command Is Non-existent $ vim example2.sh #!/bin/bash set -e foo bar echo "welcome to klug" :x $ bash example2.sh To Display an Error in Piped Commands $ vim example3.sh #!/bin/bash set -eo pipefail foobar | echo "Hi welcome to chennaipy" echo "welcome to ilugc" :x $ bash example3.sh To set allexport and notify options $ set -o allexport -o notify regards, T.Dhanasekar

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1D1C - service
by Dhanasekar 04 Feb '23

04 Feb '23

service - is used to control SysVinit services through SysVinit scripts syntax $ service [options] [service] [subcommand] To check the status of service $ sudo service rsyslog status $ sudo service sshd status To stop a service $ sudo service rsyslog stop $ sudo service sshd stop To restart a service $ sudo service rsyslog restart $ sudo service sshd restart $ sudo service vsftpd restart To list the status for all the programs $ sudo service --status-all To do a full restart $ sudo service service_name --full-restart regards, T.Dhanasekar

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1D1C - seq
by Dhanasekar 03 Feb '23

03 Feb '23

seq - print a sequence of numbers syntax $ seq [option] FIRST INCREMENT LAST To display Seq LAST , default increment is 1 $ seq 20 To print with Seq FIRST and LAST $ seq 5 20 To print Seq FIRST INCREMENT LAST $ seq 4 2 50 To add the strings before the sequence number $ seq -f NUM%02g 10 To print the formatted strings starting from 5 and incrementing by 5 up to 25 $ seq -f NUM%02g 5 5 25 To display the output on the same line $ seq -s " " 5 5 50 To append the leading zeros to equalize the width $ seq -ws " " 3 2 120 To display with separators $ seq -s - 100 To generate a sequence containing the floating values $ seq -f "%f" 2 0.5 10 regards, T.Dhanasekar

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ILUG-D February 2023