The plain sort just considers the text as a string of characters rather than a single numerical element whereas
sort -n arranges the given list of numbers numerically in the ascending order of the numerical value of each number.
wc -l < mydata.dat: this command reads from a file, mydata.dat instead of from standard input and shows the number
of lines int he file whereas wc -1 mydata.dat shows the number of lines in the file, mydata.dat. One thing that I
noticed between these two commands is that the one with the '<' does not list the filename in the output, whereas the
one without it does.
Since uniq only removes adjacent duplicated lines, the lines in the file should be sorted using sort command and then
pipe the output to the the uniq command. That is, sort salmon.txt | uniq. The reason why uniq removes just adjacent
duplicated lines is that I guess that it is just computationally easier to perform the operation on adjacent items, since
you would have to do a lot of looping if the dataset happens to be very large.
cat animals.txt command displays the content of the whole file. cat animals.txt | head -5, this command passes teh top five
content through the pipe. cat animals.txt | head -5 | tails -3, this command passes the bottom three content through the
pipe. cat animals.txt | head -5 | tails-3 | sort -r, this command sort the three content in reversed order. That is, the top
one goes to the bottom position; the middle one goes to the top position, and the bottom one goes to the middle position.
cut -d, -f 2 animals.txt: this command extract only the second field of the file delimited by comma. In order to extract
a single instance of each animals from this text file, sort and uniq commands should be added. That is, cut -d, -f 2 animals.txt
| sort | uniq
