Linuxzoo Pipes Questions: Write the commands that will execute the following Que

Question

Linuxzoo Pipes Questions: Write the commands that will execute the following

Question 6: using grep

Use grep on /usr/share/dict/words to find the first word that contains the three letter sequence wta

Question 7: count with grep

Use grep piped through wc on file /usr/share/dict/words to find the number of words that contain the letter x.

Question 8: negative grep

Use grep to find all lines in /etc/passwd that do not have nologin one the line. Make grep include the line numbers of the matching lines and send the output to file s5

Question 9: grep and ls

Use ls -l and grep to find all the files in the directory /etc that were last modified in August (hint: try looking for the case sensitive string "Aug"). Send this list to s6.

Question 10: ls grep and sort

Use ls -l and grep and sort to find all the files in /etc that were last modified in Jun. Sort this list in descending order of size and then alphabetically by name (so 2 files with the same size will appear in alphabetic order). Send the output to s7. Sorting using other techniques will probably not get the same answer...

Explanation / Answer

Question 6: Assuming there is only one such word per line,

grep -o -m 1 "wta" /usr/share/dict/words

-o would print only the word -m 1 would stop at the line where the first occurence is there

If there are multiple words per line with the same pattern, you need to pipe the above command with head

grep -o -m 1 "wta" /usr/share/dict/words | head -1. Otherwise you need to use awk or sed commands

Question 7: grep -o "x" /usr/share/dict/words | wc -w

-o prints only those words which contain the regular expression wc -w counts the number of words it receives as input

Question 8: grep -n -v "nologin" /etc/passwd > s5

-n option prints the line numbers. -v inverts the search. > operator writes to the file

Question 9: ls -l /etc | grep "Aug" > s6

Note: This sends the whole line and not only the filename

I don't know the answer for 10th one

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