# Ubuntu Kid ### This is the official guide for Ubuntu Kid International Test collected by Featurepreneur & TactLabs ## Ubuntu Ubuntu releases are made semiannually by Canonical Ltd, the developers of the Ubuntu operating system, using the year and month of the release as a version number. The first Ubuntu release was Ubuntu 4.10 and was released on 20 October 2004. An estimated 95% of all Ubuntu installations are LTS releases. Every six months between LTS versions, Canonical publishes an interim release of Ubuntu, with 20.10 being the latest example. Ubuntu, a desktop and server distribution derived from Debian, maintained by British company Canonical Ltd. Ubuntu was originally developed by Mark Richard Shuttleworth (born 18 September 1973) who is a South African-British entrepreneur and the founder and CEO of Canonical. ## Edubuntu Edubuntu, previously known as Ubuntu Education Edition, was an official derivative of the Ubuntu operating system designed for use in classrooms inside schools, homes, and communities. ## Intrepid Ibex Ubuntu 8.10 (Intrepid Ibex), released on 30 October 2008, was Canonical's ninth release of Ubuntu. Support ended on 30 April 2010. Ubuntu 8.10 introduced several new features including improvements to mobile computing and desktop scalability, increased flexibility for Internet connectivity, an Ubuntu Live USB creator, and a guest account, which allowed others to use a computer allowing very limited user rights (e.g. accessing the Internet, using software and checking e-mail). ## LibreOffice LibreOffice is a free and open-source office suite. It was forked in 2010 from OpenOffice.org, which was an open-sourced version of the earlier StarOffice. The LibreOffice suite consists of programs for word processing, creating and editing spreadsheets, slideshows, diagrams, and drawings, working with databases, and composing mathematical formulae. ## Unity Unity has been part of Ubuntu for the last 6 years and over time, it did gain its fair share of fan following. If you are one of the hardcore Unity fans and would like to use it instead of GNOME, I have good news for you. You can totally use Unity on Ubuntu 18.04 and 17.10. ## Ubuntu Commands: ## 1. alias The alias command lets you give your own name to a command or sequence of commands. You can then type your short name, and the shell will execute the command or sequence of commands for you. ``` alias cls=clear ``` This sets up an alias called cls . It will be another name for clear . When you type cls, it will clear the screen just as though you had typed clear . Your alias saves a few keystrokes, sure. But, if you frequently move between Windows and Linux command line, you can find yourself typing the Windows cls command on a Linux machine that doesn’t know what you mean. Now it will know. Aliases can be much more intricate than that simple example. Here’s an alias called pf (for process find) that is just a little more complex. Note the use of quotation marks around the command sequence. This is required if the command sequence has spaces in it. This alias uses the ps command to list the running processes and then pipes them through the grep command. The grep command looks for entries in the output from ps that match the command line parameter $1 . ``` alias pf="ps -e | grep $1" ``` If you wanted to discover the process ID (PID) of the shutter process—or to find out if shutter was even running—you could use the alias like this. Type pf, a space, and the name of the process you are interested in: ``` pf shutter ``` Aliases defined on the command line will die with the terminal window. When you close it, they are gone. To make your aliases always be available to you, add them to the`.bash_aliases` file in your home directory. ## 2. cat The `cat` command (short for “concatenate”) lists the contents of files to the terminal window. This is faster than opening the file in an editor, and there’s no chance you can accidentally alter the file. To read the contents of your `.bash_log_out` file, type the following command while the home directory is your current working directory, as it is by default: ``` cat .bash_logout ``` With files longer than the number of lines in your terminal window, the text will whip past too fast for you to read. You can pipe the output from `cat` through `less` to make the process more manageable. With `less` you can scroll forward and backward through the file using the Up and Down Arrow keys, the PgUp and PgDn keys, and the Home and End keys. Type `q` to quit from less. ``` cat .bashrc | less ``` ## 3. cd The `cd` command changes your current directory. In other words, it moves you to a new place in the filesystem. If you are changing to a directory that is within your current directory, you can simply type `cd` and the name of the other directory. ``` cd sunapana ``` If you are changing to a directory elsewhere within the filesystem directory tree, provide the path to the directory with a leading /. ``` cd /usr/local/bin ``` To quickly return to your home directory, use the `~` (tilde) character as the directory name. ``` cd ~ ``` Here’s another trick: You can use the double dot symbol `..` to represent the parent of the current directory. You can type the following command to go up a directory: ``` cd .. ``` Imagine you are in a directory. The parent directory has other directories in it, as well as the directory you’re currently in. To change into one of those other directories, you can use the `..` symbol to shorten what you have to type. ``` cd ../sunapana ``` ## 4. chmod The `chmod` command sets the file permissions flags on a file or folder. The flags define who can read, write to or execute the file. When you list files with the `-l` (long format) option you’ll see a string of characters that look like ``` -rwxrwxrwx ``` If the first character is a `-` the item is a file, if it is a `d` the item is a directory. The rest of the string is three sets of three characters. From the left, the first three represent the file permissions of the *owner*, the middle three represent the file permissions of the *group* and the rightmost three characters represent the permissions for *others*. In each set, an `r` stands for read, a `w` stands for write, and an `x` stands for execute. If the `r`, `w`, or `x` character is present that file permission is granted. If the letter is not present and a `-` appears instead, that file permission is not granted. One way to use `chmod` is to provide the permissions you wish to give to the owner, group, and others as a 3 digit number. The leftmost digit represents the owner. The middle digit represents the group. The rightmost digit represents the others. The digits you can use and what they represent are listed here: * **0:** No permission * **1:** Execute permission * **2:** Write permission * **3:** Write and execute permissions * **4:** Read permission * **5:** Read and execute permissions * **6:** Read and write permissions * **7:** Read, write and execute permissions Looking at our example.txt file, we can see that all three sets of characters are `rwx`. That means everyone has read, write and execute rights with the file. To set the permission to be read, write, and execute (7 from our list) for the *owner;* read and write (6 from our list) for the *group;* and read and execute (5 from our list) for the *others* we’d need to use the digits 765 with the `chmod` command: ``` chmod -R 765 vedimuthu.txt ``` To set the permission to be read, write and execute (7 from our list) for the *owner*, and read and write (6 from our list) for the *group* and for the *others* we’d need to use the digits 766 with the `chmod` command: ``` chmod 766 vedimuthu.txt ``` ## 5. chown The `chown` command allows you to change the owner and group owner of a file. Listing our example.txt file with `ls -l` we can see `kaipulla vvs` in the file description. The first of these indicates the name of the file owner, which in this case is the user `kaipulla`. The second entry shows that the name of the group owner is also `vvs`. (short form of Varuathapadadha Vaalibar Sangam) Each user has a default group created when the user is created. That user is the only member of that group. This shows that the file is not shared with any other groups of users. You can use `chown` to change the owner or group, or both of a file. You must provide the name of the owner and the group, separated by a `:` character. You will need to use `sudo`. To retain kaipulla as the owner of the file but to set vvs as the group owner, use this command: ``` sudo chown kaipulla:vvs example.txt ``` To change both the owner and the group owner to kaipulla, you would use the following command; ``` sudo chown kaipulla:kaipulla example.txt ``` To change the file so that kaipulla is once more the file owner and the group owner, use this command: ``` sudo chown kaipulla:kaipulla example.txt ``` ## 6. curl The `curl` command is a tool to retrieve information and files from Uniform Resource Locators (URLs) or internet addresses. The `curl` command may not be provided as a standard part of your Linux distribution. Use `apt-get` to install this package onto your system if you’re using Ubuntu or another Debian-based distribution. On other Linux distributions, use your Linux distribution’s package management tool instead. ``` sudo apt-get install curl ``` Suppose you want to retrieve a single file from a GitHub repository. There is no officially supported way to this. You’re forced to clone the entire repository. With `curl` however, we can retrieve the file we want on its own. This command retrieves the file for us. Note that you need to specify the name of the file to save it in, using the `-o` (output) option. If you do not do this, the contents of the file are scrolled rapidly in the terminal window but not saved to your computer. ``` curl https://raw.githubusercontent.com/torvalds/linux/master/kernel/events/core.c -o core.c ``` If you don’t want to see the download progress information use the `-s` (silent) option. ``` curl -s https://raw.githubusercontent.com/torvalds/linux/master/kernel/events/core.c -o core.c ``` ## 7. df The `df` command shows the size, used space, and available space on the mounted filesystems of your computer. Two of the most useful options are the `-h` (human readable) and `-x` (exclude) options. The human-readable option displays the sizes in Mb or Gb instead of in bytes. The exclude option allows you to tell `df` to discount filesystems you are not interested in. For example, the `squashfs` pseudo-filesystems that are created when you install an application with the `snap` command. ``` df -h -x squashfs ``` ## 8. diff The `diff` command compares two text files and shows the differences between them. There are many options to tailor the display to your requirements. The `-y` (side by side) option shows the line differences side by side. The `-w` (width) option lets you specify the maximum line width to use to avoid wraparound lines. The two files are called alpha1.txt and alpha2.txt in this example. The `--suppress-common-lines` prevents `diff` from listing the matching lines, letting you focus on the lines which have differences. ``` diff -y -W 70 esakki.txt sangimangi.txt --suppress-common-line ``` ## 9. echo The `echo` command prints (echoes) a string of text to the terminal window. The command below will print the words “A string of text” on the terminal window. ``` echo A string of text ``` The `echo` command can show the value of environment variables, for example, the `$USER`, `$HOME`, and `$PATH` environment variables. These hold the values of the name of the user, the user’s home directory, and the path searched for matching commands when the user types something on the command line. ``` echo $USER ``` ``` echo $HOME ``` ``` echo $PATH ``` ## 10. exit The exit command will close a terminal window, end the execution of a shell script, or log you out of an SSH remote access session. ``` exit ``` ## 11. find Use the `find` command to track down files that you know exist if you can’t remember where you put them. You must tell `find` where to start searching from and what it is looking for. In this example, the `.` matches the current folder and the `-name` option tells `find` to look for files with a name that matches the search pattern. You can use wildcards, where `*` represents any sequence of characters and `?` represents any single character. We’re using `*ones*` to match any file name containing the sequence “ones.” This would match words like bones, stones, and lonesome. ``` find . -name *embaram* ``` As we can see, `find` has returned a list of matches. One of them is a directory called Ramones. We can tell `find` to restrict the search to files only. We do this using the `-type` option with the `f` parameter. The `f` parameter stands for files. ## 12. finger The `finger` command gives you a short dump of information about a user, including the time of the user’s last login, the user’s home directory, and the user account’s full name. ## 13. free The `free` command gives you a summary of the memory usage with your computer. It does this for both the main Random Access Memory (RAM) and swap memory. The `-h` (human) option is used to provide human-friendly numbers and units. Without this option, the figures are presented in bytes. ``` free -h ``` ## 14. grep The `grep` utility searches for lines which contain a search pattern. When we looked at the alias command, we used `grep` to search through the output of another program, `ps` . The `grep` command can also search the contents of files. Here we’re searching for the word “train” in all text files in the current directory. ``` grep pulippandi *.txt ``` The output lists the name of the file and shows the lines that match. The matching text is highlighted. ## 15. groups The `groups` command tells you which groups a user is a member of. ``` groups kaipulla ``` ``` groups snakebabu ``` ## 16. gzip The `gzip` command compresses files. By default, it removes the original file and leaves you with the compressed version. To retain both the original and the compressed version, use the `-k` (keep) option. ``` gzip -k sangimangi.c ``` ## 17. head The `head` command gives you a listing of the first 10 lines of a file. If you want to see fewer or more lines, use the `-n` (number) option. In this example, we use `head` with its default of 10 lines. We then repeat the command asking for only five lines. ``` head -sunapana.txt ``` ``` head -n 5 sunapana.txt ``` ## 18. history The history command lists the commands you have previously issued on the command line. You can repeat any of the commands from your history by typing an exclamation point `!` and the number of the command from the history list. ``` !188 ``` Typing two exclamation points repeats your previous command. ``` !! ``` ## 19. kill The `kill` command allows you to terminate a process from the command line. You do this by providing the process ID (PID) of the process to `kill`. Don’t kill processes willy-nilly. You need to have a good reason to do so. In this example, we’ll pretend the `shutter` program has locked up. To find the PID of `shutter` we’ll use our `ps` and `grep` trick from the section about the `alias` command, above. We can search for the `shutter` process and obtain its PID as follows: ``` ps -e | grep shutter. ``` Once we have determined the PID—1692 in this case—we can kill it as follows: ``` kill 1692 ``` ## 20. less The `less` command allows you to view files without opening an editor. It’s faster to use, and there’s no chance of you inadvertently modifying the file. With `less` you can scroll forward and backward through the file using the Up and Down Arrow keys, the PgUp and PgDn keys and the Home and End keys. Press the Q key to `quit` from `less`. To view a file provide its name to `less` as follows: ``` less snakebabu.txt ``` You can also pipe the output from other commands into `less`. To see the output from `ls` for a listing of your entire hard drive, use the following command: ``` ls -R / | less ``` Use `/` to search forward in the file and use `?` to search backward. ## 21. ls This might be the first command the majority of Linux users meet. It lists the files and folders in the directory you specify. By default, `ls` looks in the current directory. There are a great many options you can use with `ls` , and we strongly advise reviewing its the man page. Some common examples are presented here. To list the files and folders in the current directory: ``` ls ``` To list the files and folders in the current directory with a detailed listing use the `-l` (long) option: ``` ls -l ``` To use human-friendly file sizes include the `-h` (human) option: ``` ls -lh ``` To include hidden files use the `-a` (all files) option: ``` ls -lha ``` ## 22. man The man command displays the “man pages” for a command in `less` . The man pages are the user manual for that command. Because `man` uses `less` to display the man pages, you can use the search capabilities of `less`. For example, to see the man pages for `chown`, use the following command: ``` man chown ``` Use the Up and Down arrow or PgUp and PgDn keys to scroll through the document. Press `q` to quit the man page or press`h` for help.
## 23. mkdir The `mkdir` command allows you to create new directories in the filesystem. You must provide the name of the new directory to `mkdir`. If the new directory is not going to be within the current directory, you must provide the path to the new directory. To create two new directories in the current directory called “pulikesi” and “vvs,” use these two commands: ``` mkdir pulikesi ``` ``` mkdir vvs ``` To create a new directory called “2019” inside the “pulikesi” directory, use this command: ``` mkdir pulikesi/2109 ``` If you are going to create a directory, but its parent directory does not exist, you can use the `-p` (parents) option to have `mkdir` create all of the required parent directories too. In the following command, we are creating the “vadivelu” directory inside the “vvs” directory inside the “kaipulla” directory. The “vvs” directory does not exist, but we can have `mkdir` create all the specified directories at once: ``` mkdir -p vadivelu/vvs/kaipulla ``` The “vvs” directory is also created. ## 24. mv The `mv` command allows you to move files and directories from directory to directory. It also allows you to rename files. To move a file you must tell `mv` where the file is and where you want it to be moved to. In this example, we’re moving a file called `kaipulla.pdf` from the “\~/Document/Vadivelu” directory and placing it in the current directory, represented by the single `.` character. ``` mv ~/Documents/Vadivelu/kaipulla.pdf . ``` To rename the file, you “move” it into a new file with the new name. ``` mv kaipulla.pdf The_great_kaipulla.pdf ``` The file move and rename action could have been achieved in one step: ``` mv ~/Documents/Vadivelu/kaipulla.pdf ./The_great_kaipulla.pdf ``` ## 25. passwd The `passwd` command lets you change the password for a user. Just type `passwd` to change your own password. You can also change the password of another user account, but you must use `sudo`. You will be asked to enter the new password twice. ``` sudo passwd snakebabu ``` ## 26. ping The `ping` command lets you verify that you have network connectivity with another network device. It is commonly used to help troubleshoot networking issues. To use `ping`, provide the IP address or machine name of the other device. ``` ping 192.168.4.18 ``` The `ping` command will run until you stop it with Ctrl+C. Here’s what’s going on here: * The device at IP address 192.168.4.18 is responding to our ping requests and is sending back packets of 64 bytes. * The Internet Control Messaging Protocol (ICMP) sequence numbering allows us to check for missed responses (dropped packets). * The TTL figure is the “time to live” for a packet. Each time the packet goes through a router, it is (supposed to be) decremented by one. If it reaches zero the packet is thrown away. The aim of this is to prevent network loopback problems from flooding the network. * The time value is the duration of the round trip from your computer to the device and back. Simply put, the lower this time, the better. To ask `ping` to run for a specific number of ping attempts, use the `-c` (count) option. ``` ping -c 5 192.168.4.18 ``` To hear a ping, use the `-a` (audible) option. ``` ping -a 192.168.4.18 ``` ## 27. ps The `ps` command lists running processes. Using `ps` without any options causes it to list the processes running in the current shell. ``` ps ``` To see all the processes related to a particular user, use the `-u` (user) option. This is likely to be a long list, so for convenience pipe it through `less`. ``` ps -u kaipulla | less ``` To see every process that is running, use the `-e` (every process) option: ``` ps -e | less ``` ## 28. pwd Nice and simple, the `pwd` command prints the working directory (the current directory) from the root / directory. ``` pwd ``` ## 29. shutdown The shutdown command lets you shut down or reboot your Linux system. Using `shutdown` with no parameters will shut down your computer in one minute. ``` shutdown ``` To shut down immediately, use the `now` parameter. ``` shutdown now ``` You can also schedule a shutdown and inform any logged in users of the pending shutdown. To let the `shutdown` command know when you want it to shut down, you provide it with a time. This can be a set number of minutes from now, such as `+90` or a precise time, like `23:00`. Any text message you provide is broadcast to logged in users. ``` shutdown 23:00 Shutdown tonight at 23:00, save your work and log out before then! ``` shutdown 23:00 Shutdown tonight at 23:00, save your work and log out before then! ``` shutdown +15 Shutting down in 15 minutes! ``` ``` shutdown -c ``` ## 30. SSH Use the ssh command to make a connection to a remote Linux computer and log into your account. To make a connection, you must provide your user name and the IP address or domain name of the remote computer. In this example, the user kaipulla is logging into the computer at 192.168.4.23. Once the connection is established, he is asked for her password. ``` ssh kaipulla@192.168.4.23 ``` His user name and password are verified and accepted, and he is logged in. Notice that his prompt has changed from “Nostromo” to “howtogeek.” Kaipulla issues the `w` command to list the current users on “howtogeek” system. She is listed as being connected from pts/1, which is a pseudo-terminal slave. That is, it is not a terminal directly connected to the computer. To close the session, kaipulla types `exit` and is returned to the shell on the “Nostromo” computer. ``` w ``` ``` exit ``` ## 31. sudo The `sudo` command is required when performing actions that require root or superuser permissions, such as changing the password for another user. ``` sudo passwd kaipulla ``` ## 32. tail The `tail` command gives you a listing of the last 10 lines of a file. If you want to see fewer or more lines, use the `-n` (number) option. In this example, we use `tail` with its default of 10 lines. We then repeat the command asking for only five lines. ``` tail core.c ``` ``` tail -n 5 core.c ``` ## 33. tar With the `tar` command, you can create an archive file (also called a tarball) that can contain many other files. This makes it much more convenient to distribute a collection of files. You can also use `tar` to extract the files from an archive file. It is common to ask `tar` to compress the archive. If you do not ask for compression, the archive file is created uncompressed. To create an archive file, you need to tell `tar` which files to include in the archive file, and the name you wish the archive file to have. In this example, the user is going to archive all of the files in the Ukulele directory, which is in the current directory. They have used the `-c` (create) option and the `-v` (verbose) option. The verbose option gives some visual feedback by listing the files to the terminal window as they are added to the archive. The `-f` (filename) option is followed by the desired name of the archive. In this case, it is `songs.tar`. ``` tar -cvf songs.tar Ukulele/ ``` The files are listed to the terminal window as they are added to the archive file. There are two ways to tell `tar` that you want the archive file to be compressed. The first is with the `-z` (gzip) option. This tells tar to use the `gzip` utility to compress the archive once it has been created. It is usual to add “.gz” as suffix to this type of archive. That allows anyone who is extracting files from it to know which commands to pass to `tar` to correctly retrieve the files. ``` tar -cvzf songs.tar.gz Ukulele/ ``` The files are listed to the terminal window as they are added to the archive file as before, but the creation of the archive will take a little longer because of the time required for the compression. To create an archive file that is compressed using a superior compression algorithm giving a smaller archive file use the `-j` (bzip2) option. ``` tar -cvjf songs.tar.bz2 Ukulele/ ``` Once again, the files are listed as the archive is created. The `-j` option is noticeably slower than the `-z` option. If you are archiving a great many files, you must choose between the `-z` option for decent compression and reasonable speed, or the `-j` option for better compression and slower speed. As can be seen in the screenshot below, the “.tar” file is the largest, the “.tar.gz” is smaller, and the “.tar.bz2” is the smallest of the archives. To extract files from an archive file use the `-x` (extract) option. The `-v` (verbose) and `-f` (filename) options behave as they do when creating archives. Use `ls` to confirm which type of archive you are going to extract the files from, then issue the following command. ``` ls ``` ``` tar -xvf songs.tar ``` The files are listed as they are extracted. Note that the Ukulele directory is also recreated for you. To extract files from a “.tar.gz” archive, use the `-z` (gzip) option. ``` tar -xvzf songs.tar.gz ``` Finally, to extract files from a “.tar.bz2” archive use the `-j` option instead of the `-z` (gzip) option. ``` tar -xvjf songs.tar.bz2 ``` ## 34. top The `top` command shows you a real-time display of the data relating to your Linux machine. The top of the screen is a status summary. The first line shows you the time and how long your computer has been running for, how many users are logged into it, and what the load average has been over the past one, five, and fifteen minutes. The second line shows the number of tasks and their states: running, stopped, sleeping and zombie. The third line shows CPU information. Here’s what the fields mean: * us: value is the CPU time the CPU spends executing processes for users, in “user space” * sy: value is the CPU time spent on running system “kernel space” processes * ni: value is the CPU time spent on executing processes with a manually set nice value * id: is the amount of CPU idle time * wa: value is the time the CPU spends waiting for I/O to complete * hi: The CPU time spent servicing hardware interrupts * si: The CPU time spent servicing software interrupts * st: The CPU time lost due to running virtual machines (“steal time”) The fourth line shows the total amount of physical memory, and how much is free, used and buffered or cached. The fifth line shows the total amount of swap memory, and how much is free, used and available (taking into account memory that is expected to be recoverable from caches).\ The user has pressed the E key to change the display into more humanly digestible figures instead of long integers representing bytes. The columns in the main display are made up of: * PID: Process ID * USER: Name of the owner of the process * PR: Process priority * NI: The nice value of the process * VIRT: Virtual memory used by the process * RES: Resident memory used by the process * SHR: Shared memory used by the process * S: Status of the process. See the list below of the values this field can take * %CPU: the share of CPU time used by the process since last update * %MEM: share of physical memory used * TIME+: total CPU time used by the task in hundredths of a second * COMMAND: command name or command line (name + options) (The command column didn’t fit into the screenshot.) The status of the process can be one of: * D: Uninterruptible sleep * R: Running * S: Sleeping * T: Traced (stopped) * Z: Zombie Press the Q key to exit from `top`. ## 35. uname You can obtain some system information regarding the Linux computer you’re working on with the `uname` command. * Use the `-a` (all) option to see everything. * Use the `-s` (kernel name) option to see the type of kernel. * Use the `-r` (kernel release) option to see the kernel release. * Use the `-v` (kernel version) option to see the kernel version. ``` uname -a ``` ``` uname -s ``` ``` uname -r ``` ``` uname -v ``` ## 36. w The `w` command lists the currently logged in users. ``` w ``` ## 37. whoami Use `whoami` to find out who you are logged in as or who is logged into an unmanned Linux terminal. ``` whoami ``` ## 38. lsof lsof means "list open files", used to display list of all open files along with the processes that caused it to open. ``` $lsof ``` ## 39. dpkg The dpkg command is used to manage and work with the debian files ``` dpkg --list ``` The --list is used to list all installed packages ## 40. cp The command cp provides a way to make a copy of the file specified and store it in the destination ``` $ cp $ cp ``` ## 41. rmdir The command rmdir is used to remove a speciifed directory ``` $ rmdir $ rmdir sample.txt ``` ## 42. gedit The gedit utility allows user to open a file in gedit text editor $ gedit ``` $ gedit hello.html ``` ## 43. unzip The unzip command is used to decompress a zipped file and to extract the files present in it ``` $ unzip $ unzip testfile ``` ## 44. date The date command is used to display the current date along with time and timezone ``` $ date Sunday 20 December 2020 11:31:30 AM IST ``` If you wish to set a Time zone, it can be done by using export command ``` $ export TZ=America/Los_Angeles ``` ``` $ date Saturday 19 December 2020 10:03:19 PM PST ``` To remove the value set, you can use unset command. ``` $ unset TZ ``` ``` $ date Sunday 20 December 2020 11:32:45 AM IST ``` You can also set the current date and time manually using --set option ``` $ date --set ``` ## 45. uptime The uptime command is used to display information about how long the system been running, along with the number of users currently running processes on the system and the load averages fo teh past 1, 5 and 25 minutes separated by comma. ``` $ uptime 22:18:55 up 2:52, 1 user, load average: 0.55, 0.78, 0.83 ``` ## 46. whereis Used to display the path of any specified builtin commands ``` $ whereis ls ls: /usr/bin/ls /usr/share/man/man1/ls.1. ``` ## 47. lsusb The lsusb command provides you with the information about USB buses in the system and the devices connected to them. ``` $ lsusb ``` ## 48. Copy, paste in terminal ``` Ctrl + Shift + C Used to copy the contents in terminal ``` ``` Ctrl + Shift + V Used to paste contents of the clipboard in terminal ``` ## 49. Multiple commands in a single line Commands can be separated by double ambersand (&&) ``` $ mkdir sunapana && cd sunapana ``` ## 50. type The Type command is used to find out the information about a Linux command. It is also used to find whether the given command is an alias, shell built-in, file, function, or keyword. Additionally, you can find the actual path of the command too. ``` $ type ``` To find absolute path of the command, use -p option\\ ``` $ type -p ``` To display all the information, you can use -a option ``` $ type -a ``` ## 51. ss The command is used to display all the current socket status of the system ``` $ ss ``` ## 52. clear The clear command is used to clear the screen of the terminal. ``` $ clear ``` ## 53. du The du command means "disk usage", as the name suggests it allows a user to know disk usage information. ``` $ du ``` If you want to calculate the size of a particular folder​, use -sh command. ``` $du –sh snakebabu ``` ## 54. ps To find the status of a process, use can use ux option ``` $ ps ux ``` ``` $ ps us -m ``` The command -m is used to display memory status in MB ``` $ ps us -g ``` The command -g is used to display memory status in GB ## 55. fstab The configuration file /etc/fstab contains the necessary information to automate the process of mounting partitions. In a nutshell, mounting is the process where a raw (physical) partition is prepared for access and assigned a location on the file system tree (or mount point). ## 56. **zip** If you have a zipped folder, then we can use the zip command with ‘sf‘ options to view all the contents of the zipped folder, ``` $ zip -sf pachakizhi.zip ``` ## 57. less we can also use ‘less command‘ to view the contents of the above-mentioned archive extensions. ``` $ less sunapana.tgz ``` ## 58. tar If we have an archived folder with tar as an extension, we can check the contents of the archive by using the tar command with option ‘t’. For examples, ``` $ tar -tvf snakebabu.tar ``` ## 59. df Display filesystem inode space information: By default, the df command summarizes available and used disk space. You can instead receive a report on available and used inodes bypassing the -i or --inodes option. ``` $ df -i ``` The simplest df command is by itself. Without any command parameters. When executed the df command displays the information about the file system disk space usage. It shows the device name, total blocks, total disk space, used disk space, free disk space and mount points. Using the df command with -a or –all it shows dummy file systems information along with all the basic file system disk usage info ``` df -a ``` As the disk space is shown in 1K blocks by default, users can use “-h” command parameter to show the file system disk space usage data in “human readable” format. ``` df -h ``` Use the command parameters -hT to display the info about the /home file system ``` df -hT /home ``` Use the command argument -k to display all file system information in 1024-byte blocks ``` df -k ``` Similarly you can use the command argument -m to display all file system information in MB (Mega Byte) and -h to see the info in GB (Gigabyte) ``` df -m ``` If you wish to see the disk space usage info of a certain file system type, use it as argument ``` df -t ext3 ``` src:\ --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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