also sprach Martin McCormick <martin@dc.cis.okstate.edu> [2005.02.11.1846 +0100]: > sed is one of my favorite UNIX applications and I see examples > of expressions that I have read about but hadn't tried so this is a > good learning experience. The -ne tells sed to quietly use the next field > which is the part in single quotes as a regular expression > 's,[:space:]install$,,p' > > Here's where I think a switch is in the opposite position so > to speak. This produces a perfect list of every deinstalled package > on the system, some white space and then a single d. man, this is not my day. use [[:space:]] instead of [:space:]. > The part of the sed expression I am not familiar with is the > very last part of the quoted block that says > $,,p The white space before the word install is the trigger. it's basically a grep and sed combined: replace "[[:space:]]install" at the end of the line with nothing and only print (-n inhibits automatic printing) lines where the replacement took place. you could also do it with grep and awk: grep '[[:space:]]install$' | awk '{print$1}' but why spawn two processes when one suffices? -- Please do not send copies of list mail to me; I read the list! .''`. martin f. krafft <madduck@debian.org> : :' : proud Debian developer, admin, user, and author `. `'` `- Debian - when you have better things to do than fixing a system Invalid/expired PGP subkeys? Use subkeys.pgp.net as keyserver!
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