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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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1D1C - timedatectl
by Dhanasekar 03 Apr '23

03 Apr '23

timedatectl - Control the system time and date To display the current settings $ timedatectl To Show current time settings $ timedatectl status To Show properties of systemd-timedated $ timedatectl show To change settings $ sudo timedatectl set-timezone Asia/Hong_Kong $ sudo timedatectl set-timezone Asia/Tokyo To list the time zones $ timedatectl list-timezones | column To display the number of time-zones available $ timedatectl list-timezones | wc -l To Show status of systemd-timesyncd $ timedatectl timesync-status To Show properties of systemd-timesyncd $ timedatectl show-timesync To Show all properties, including empty ones $ timedatectl -a To Set system time $ timedatectl set-time <TIME> To Set system time zone $ timedatectl set-timezone <ZONE> To Show this help options $ timedatectl --help regards, T.Dhanasekar

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1D1C - tgz
by Dhanasekar 02 Apr '23

02 Apr '23

tgz - makes a gzip'd tar archive syntax $ tgz [ destination [ source ... ] ] $ tar -cvzf <name of tarball>.tgz /path/to/source/folder $ tar -cvzf <name of tarball>.tgz /path/to/source_file $ tar -cvzf file.tgz /home/ilugc/Documents/file.pdf regards, T.Dhanasekar

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1D1C - time
by Dhanasekar 02 Apr '23

02 Apr '23

time - run programs and summarize system resource usage syntax $ time [options] [command] Real: This is the actual time taken by the processor of the computer to execute the command from pressing the button to complete the command. User: CPU time that is taken by the user mode. SYS: This is the time taken by the system or the Kernel to execute the command. To calculate execution time of commands $ time sleep 5 $ time free -h $ time df -Th $ time ping google.com To display the time in portable POSIX format $ time -p sleep 5 $ time -p free -h $ time -p df -Th $ time -p ping google.com To calculate the update time $ time sudo apt update To save the time command output in the text file $ /usr/bin/time -o sleep_output.txt sleep 5 $ /usr/bin/time -o df_output.txt df -Th To get detailed summary of the executed time $ /usr/bin/time -v sleep 5 $ /usr/bin/time -v df -Th $ /usr/bin/time -v free -h regards, T.Dhanasekar

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1D1C - test
by Dhanasekar 31 Mar '23

31 Mar '23

test - check file types and compare values To print “Yes, that’s true.” when 100 is greater than 99. $ test 100 -gt 99 && echo "Yes, that's true." || echo "No, that's false." To print "No, that's false." when 99 is greater than 100. $ test 99 -gt 100 && echo "Yes, that's true." || echo "No, that's false." To check if a file exists and is a regular file $ test -f /etc/resolv.conf && echo "File /etc/resolv.conf found." || echo "File /etc/resolv.conf not found." $ test -f /etc/ssh/sshd_config && echo "File /etc/ssh found." || echo "File /etc/ssh not found." To print 0 when the expression is true and two strings are identical. $ [ "awesome" = "awesome" ]; echo $? To print 1 when the expression is false and two strings are not identical. $ [ "awesome" = "1awesome" ]; echo $? To print "1" because the expression is false $ [ 7 -eq 10 ]; echo $? To print "0" because the expression is true $ [ 10 -eq 10 ]; echo $? regards, T.Dhanasekar

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1D1C - telnet
by Dhanasekar 30 Mar '23

30 Mar '23

telnet - is used for interactive communication with another host using the TELNET protocol $ telnet -l [username] [remote machine IP] [port (optional)] To connect to the device with specific IP address $ telnet 192.168.122.105 To quit the connected machine $ logout To connect remote server with user and port number $ telnet -l remote_user 192.168.122.105 3000 To connect to the telnet shell $ telnet telnet> To print help options $ telnet telnet > h To exit the telnet shell telnet > quit regards, T.Dhanasekar

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1D1C - telinit
by Dhanasekar 29 Mar '23

29 Mar '23

telinit - Change SysV runlevel syntax $ sudo telinit [options] {runlevel} To change the runlevel for a system without rebooting or changing the /etc/inittab $ sudo telinit 0 halt $ sudo telinit 1 single-user mode $ sudo telinit 2 Not used (user-definable) $ sudo telinit 3 Full multi-user mode $ sudo telinit 4 Not used (user-definable) $ sudo telinit 5 Full multi-user mode (with an X-based login screen) $ sudo telinit 6 Reboot $ sudo telinit q Reload daemon configuration equivalent systemctl daemon-reload regards, T.Dhanasekar

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1D1C - tcpdump
by Dhanasekar 26 Mar '23

26 Mar '23

tcpdump - prints out a description of the contents of packets on a network interface To capture packets from Specific Interface $ sudo tcpdump -i eth1 To capture only N number of packets $ sudo tcpdump -c 4 -i eth1 To display the package in ASCII format $ sudo tcpdump -A -i eth1 To Display Available Interfaces $ sudo tcpdump -D To Display Captured Packets in HEX and ASCII $ sudo tcpdump -XX -i eth1 To capture and save packets in a file $ sudo tcpdump -w 0002.pcap -i eth1 To read captured packets file $ sudo tcpdump -r 0002.pcap To capture IP address packets $ sudo tcpdump -n -i eth1 To capture only TCP packets. $ sudo tcpdump -i eth1 tcp To capture packet from specific port $ sudo tcpdump -i eth1 port 22 To capture packets from source IP $ sudo tcpdump -i eth1 src 192.168.122.50 To capture packets from destination IP $ sudo tcpdump -i eth1 dst 192.168.122.100 regards, T.Dhanasekar

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