grep and sed

Find text matching a pattern in log files and command output using the grep command and regular expressions.

Task 1:

Find the rows that contain abcde from file /etc/testfile, and write it to the file /tmp/testfile, and the sequence is requested as the same as /etc/testfile

Solution:

vim /etc/testfile  # add some lines which contains abcde
grep 'abcde' /etc/testfile > /tmp/testfile

Task 2:

Download the document from ftp://instructor.example.com/pub/testfile, find all lines containing abcdeand redirect to /mnt/answer document, then rearrange the order according the original content.

Solution:

wget ftp://instructor.example.com/pub/testfile
grep '[abcde]' /tmp/testfile > /mnt/answer
grep '[abcde]' /tmp/answer

Task 3:

Find all lines in the file /usr/share/mime/packages/freedesktop.org.xml that contain the string ich. Put a copy of these lines in the original order in the file /root/lines. /root/lines should maintain contain no empty lines and all lines must be exact copies of the original lines in /usr/shre/mime/packages/freedesktop.org.xml

Solution:

grep ich /usr/share/mime/package/freedesktop.org.xml > /root/lines
sed -i '/^$/d' /root/lines
cat /root/lines

Task 4:

Find all lines in the file /usr/share/dict/wordsthat contain the string seismic. Put a copy of all these lines in their original order in the file /root/wordlist. /root/wordlistshould contain no empty lines and all lines must be exact copies of the original lines in /usr/share/dict/words

Solution:

grep seismic /usr/share/dict/words > /root/wordlist
sed -i '/^$/d/' /root/wordlist
grep seismic /root/wordlist

Task 5:

Search the string nologin in the /etc/passwdfile and save the output in /root/strings

Solution:

grep nologin /etc/passwd > /root/strings
grep nologin /root/strings