Homework & Coursework Questions

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1. The problem statement, all variables and given/known data:

The uniq command excludes consecutive duplicate lines. It has a -c option to display a count of the number of occurances of each line.

-using the man pages as necessary, analyze the following command:

history | cut -c 8-100 | cut -d " " -f 1 | sort | uniq -c

2. Relevant commands, code, scripts, algorithms:



3. The attempts at a solution (include all code and scripts):

This was the results from running the command. I have no clue what the command is doing and how the it got the results. Could someone please explain what this command is doing?

william.makarevich@socrates:/home/801NANBEA$ history | cut -c 8-100 | cut -d " " -f 1 | sort | uniq -c
2 ~
2 Andy
2 Anne
6 awk
5 cal
25 cat
11 cd
1 chgrp
2 Claudia
27 clear
1 ~clear
1 cls
7 cp
1 cut
2 %D
2 Danny
85 date
1 ~date
1 del
2 Dennis
3 diff
6 echo
1 env
8 exit
2 grep
1 groups
4 head
1 hist
16 history
2 hostname
1 id
2 Jeff
2 Lewis
2 Lisa
1 list
25 ls
51 man
1 ~man
2 Mickey
2 Mini
3 mkdir
1 more
1 msn
2 mv
1 ps
14 pwd
3 q
1 :q
1 Q
1 QQ
4 quit
1 :quit
2 Rex
4 rm
1 rmdir
2 Robert
2 Ruby
1 Sat,
2 Sherelene
4 sort
2 spell
4 tail
2 Tony
1 touch
2 Vermont
14 vi
5 wc
2 which
2 Wilbert
2 william.makarevich@socrates:~$
2 Williams
2 Yoga
2 ZZ


4. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course):

Colorado Tech University
Colorado Springs, CO, USA
Professor: Matt Hodges
Course # CS146

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Hi.

It might be easier to understand if you build up the command

Code:

history | cut -c 8-100 | cut -d " " -f 1 | sort | uniq -c

step by step, and see what differences there are.

First run

Code:

history

(this shows the commands the current logged-in user has run)

A pipe (the | character) feeds the output of one command as input to the next command, so...

Code:

history | cut -c 8-100

Will "feed" the output of the history command into the cut command.
(if you'd read the man pages as suggested, you'd know how cut works - this takes characters 8 through to 100)

sort will, sort the output of it's input (the output of the cut command - alphabetically.

uniq -c will remove duplicated (on sorted date - the previous command did that), and show the count (-c).