:* xUnderstand the purpose and why links are used in Unix / Linux

:* xDefine the term '''inode''' number as it relates to a file on Unix / Linux

:* xDefine the terms: '''Hard''' Link and '''Symbolic''' Link

:* xIssue the '''ln''' command to create hard and symbolic links :* Define and understand the purpose of a '''process''' in Unix / Linux :* '''Run''' and '''terminate''' processes in the foreground and background :* '''Display''' and '''manipulate''' background and foreground processes<br>

* Symbolic Links<br><br>

|colspan="1" style="padding-left:15px;" width="30%"|Brauer Instructional Videos:<ul><li>x[https://www.youtube.com/watch?v=tZ94-qH9unM&list=PLU1b1f-2Oe90TuYfifnWulINjMv_Wr16N&index=9 Inodes and Links]<br/li><brli>[https://www.youtube.com/watch?v=q93POTgH-aQ&list=PLU1b1f-2Oe90TuYfifnWulINjMv_Wr16N&index=7 Processes and Jobs]</li></ul>

x''Links are powerful and add flexibility to Linux filesystems because everything is a file.<br><br>There are two types of Linux filesystem links: hard and soft. The difference between the two types of links is significant, but both types are used to solve similar problems. They both provide multiple directory entries (or references) to a single file, but they do it quite differently.'' <br><br>Reference: https://opensource.com/article/17/6/linking-linux-filesystem  '''inode (index) Number of a File:''' <table align="right"><tr valign="top"><td>[[Image:inode-number-1.png|thumb|right|300px|Each inode stores the attributes and disk block locations of the object's data.<br>(Image licensed under [https://creativecommons.org/licenses/by-sa/3.0/ cc])]]</td><td>[[Image:inode-number-2.png|thumb|right|400px|The '''inode number''' is like a '''finger-print''', and usually is '''unique''' for each file on the Unix / Linux file system.]]</td></tr></table>''The inode (index node) is a data structure in a Unix-style file system that describes a file-system object such as a file or a directory. Each inode stores the attributes and disk block locations of the object's data. File-system object attributes may include metadata (times of last change, access, modification), as well as owner and permission data.'' Reference: https://en.wikipedia.org/wiki/Inode  The '''inode number''' is like a '''finger-print''', and usually is '''unique''' for each file on the Unix / Linux file system.<br>Referring to the diagram on the far right, issuing the '''ls''' command with the '''-i''' option<br>displays the inode number for each file. You can see that <u>each</u> file<br>(whether it is a directory or regular file) has its own unique inode number.   '''Hard Links:''' <table align="right"><tr valign="top"><td>[[Image:hard-link-1.png|thumb|right|300px|(Image licensed under [https://creativecommons.org/licenses/by-sa/3.0/ cc])<br>Image manipulated by author]]]</td><td>[[Image:inode-number-3.png|thumb|right|400px|(Image licensed under [https://creativecommons.org/licenses/by-sa/3.0/ cc])]]</td></tr></table>Hard link is a reference to the physical data on a file systemMore than one hard link can be associated with the same physical dataHard links can only refer to data that exists on thesame file systemHard links cannot be created to a directoryWhen a file has more than one link, you can remove any one link and still be able to access the file through the remaining links

xAll programs that are executing on a UNIX system are referred to as processesEach process has an ownerEach process has a unique ID (PID) Processes in UNIX can run in:ForegroundBackground [[Image:process-diagram-1.png|thumb|right|300px|(Image licensed under [https://creativecommons.org/licenses/by-sa/3.0/ cc])]]]UNIX processes are hierarchicalThis structure has a root, parents, and childrenCreation of a new process is called forking or spawningParent can fork a child and children can fork their own childrenProcesses keep their PID for their entire lifeUsually a parent sleeps when a child is executing– The exception is when the child process is executing in the background  ps (process status) command displays snapshot information about processesBy default, the ps command displays information only about the current terminal (ps -U username shows all)The top command provides a continuous update including resource usage

# xWrite a single Linux command to create a hard link called '''~/backup/myfile.txt.lnk''' to the existing file called '''~/myfile.txt'''<br>Write a single Linux command to display detailed information for those files above displaying their i-node numbers.<br>In this case, will the inode numbers for those files above be the same or different?<br><br># x # x# x# x# x# x# xWrite a single Linux command to create a symbolic link called '''~/shortcuts/murray.saul.lnk''' to the existing directory called '''~murray.saul'''<br>Write a single Linux command to display detailed information for those files above displaying their i-node numbers.<br>In this case, will the inode numbers for those files above be the same or different?<br><br>What data is contained in the file called '''~/shortcuts/murray.saul.lnk'''?<br>What would be the size of the file called '''~/shortcuts/murray.saul.lnk'''?<br><br># Create Write a single Linux command to run the program called '''table~/clean.sh''' listing each Linux in the background.<br>What command would you issue to place the previously issued program in the foreground?<br>What command, useful options would you issue to confirm that were mentioned this program is running in the online assignment background?<br>What key-combination would you issue to send that program again into the background?<br><br># Write a single Linux command to display running processes in “real-time”.#1 and Write a single Linux command purpose for to terminal a process that has the following Linux commandsPID: '''x22384''' , # Use the following diagram to answer the accompanying questions.<br>Each of the following questions will use the diagram below and are treated as independent situations.<br><br><span style="font-family:courier;font-weight:bold;">[1] Stopped vim a<br>[2]- Stopped vim b<br>[3]+ Stopped vim c</span><br><br>Write a single Linux command to bring the second-recently process placed in the background into the foreground.<br>Write a single Linux command to terminate the '''xjob #3''' , .<br><br># Create a '''xtable''' listing each Linux command, useful options and command purpose for the following Linux commands: '''xln''' , '''xps''' , '''xtop''' , '''xfg''' , '''xbg''' , '''xjobs''' , '''xkill'''

[[Tutorial8: Regular ExpressionsLinks / Process Management]]