Question

I want convert this text:

qa-ops01.mysite.com
/dev/mapper/sys-home   58G   26G   30G  47% /home
/dev/mapper/sys-tmp   3.9G  2.3G  1.5G  61% /tmp
qa-ops02.mysite.com
/dev/mapper/sys-home   58G   26G   30G  47% /usr
/dev/mapper/sys-tmp   3.9G  2.3G  1.5G  61% /var
qa-ops03.mysite.com
/dev/mapper/sys-home   58G   26G   30G  47% /lib
/dev/mapper/sys-tmp   3.9G  2.3G  1.5G  61% /etc

to this one:

qa-ops01.mysite.com /dev/mapper/sys-home   58G   26G   30G  47% /home
qa-ops01.mysite.com /dev/mapper/sys-tmp   3.9G  2.3G  1.5G  61% /tmp  
qa-ops02.mysite.com /dev/mapper/sys-home   58G   26G   30G  47% /usr
qa-ops02.mysite.com /dev/mapper/sys-tmp   3.9G  2.3G  1.5G  61% /var   
qa-ops03.mysite.com /dev/mapper/sys-home   58G   26G   30G  47% /lib
qa-ops03.mysite.com /dev/mapper/sys-tmp   3.9G  2.3G  1.5G  61% /etc

I have used

cat FILE |sed 'N;s/.com\n//'

Is there anyway to achieve this, or should I just write the If… Then…

Thanks everybody for the answers 😀 (you always show me new things :D)

Answer 1

The answer by potong is almost correct; it only handles one server, rather than multiple servers, but the change required is small.

$ sed -e '/^[^ ]*$/{h;d;}' -e 'G; s/\(.*\)\n\(.*\)/\2 \1/' data
qa-ops01.mysite.com /dev/mapper/sys-home   58G   26G   30G  47% /home
qa-ops01.mysite.com /dev/mapper/sys-tmp   3.9G  2.3G  1.5G  61% /tmp
qa-ops02.mysite.com /dev/mapper/sys-home   58G   26G   30G  47% /usr
qa-ops02.mysite.com /dev/mapper/sys-tmp   3.9G  2.3G  1.5G  61% /var
qa-ops03.mysite.com /dev/mapper/sys-home   58G   26G   30G  47% /lib
qa-ops03.mysite.com /dev/mapper/sys-tmp   3.9G  2.3G  1.5G  61% /etc
$

The script is in two parts, identified by the two -e options. The first part identifies server names; those lines contain no spaces (hence /^[^ ]*$/ looks for a line with no spaces), and copies the line into the hold space (h) and then deletes it (d) and continues with the next line. The second part of the script is only exercised on lines that contain spaces. It appends the content of the hold space to the pattern space after a newline (G); then it splits the line into ‘everything up to the newline’ and ‘everything after the newline’, and switches them so that the ‘after’ (\2) comes first, then a space, then the ‘before’ (\1).

This uses the classic sed regular expressions; it was tested on Mac OS X (10.7.5) with both the BSD sed and also with GNU sed without change. GNU sed has options such as -r to change the interpretation of regexes which would save you a few backslashes.