Hacker News readers probably have at least a passing familiarity with Unix/Linux, but it's still refreshing to be reminded that you can move mountains with short commands.
And even for someone who knows all of this, knowing a good guide makes it easy to handle requests for help (often preemptively). This is one I can (and just did) send to a friend who's less familiar with Unix.
Even after using linux command line for years it is always useful to see how others use it. I tend to overuse perl regex's to massage the data how I want it and underuse awk.
my norm is
cat file | perl -p -e "s/.from ([0-9\.]+) ./\1/g"
to get the ip out of the same datafile.
regex's seem to help with messy data or data that contains inconsistent delimiters.
(some of the stars got stripped by HN so the above won't work)
For my part, I don't use awk for anything more complicated than one-liners. I used it for a while, stopped when I was working on something else, and forgot all the awk-specific stuff.
My MO these days is if it's anything more complicated than an awk one-liner like awk '{print $2 " " $NF}', I'll use Python or, lately, Ruby. (Perl would be fine, too, if I used it in other contexts often enough.)
That said, there's nothing quite like, well, programming your environment. The extent to which you can manipulate files, directories, and text in *nix right out of the box makes me feel privileged to understand it. I can remember a time when renaming a bunch of images en masse seemed tantalizing but out of reach. I've since learned quite a bit, and even though it's relatively mundane now, it still feels magical. Upthread, someone called it "moving mountains." That's precisely it, and I love it.
As others have mentioned, tr and cut are extremely useful. Although I had overlooked them in the past, expand/unexpand are also very useful! They convert tabs to spaces, or spaces to tabs. Of course there are other ways to do that, like substituting with sed, translating with tr, or printing tabbed data using $1/$2/etc. with awk... they just aren't as simple.
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[ 4.8 ms ] story [ 44.7 ms ] threadWhich I guess just goes to reinforce the Unix philosophy of tools that do one job and do it well.
http://www.gnu.org/software/coreutils/manual/html_node/Openi...
http://www.gnu.org/software/coreutils/manual/ To read on the command line, try:
info coreutils
Also see,
http://en.wikipedia.org/wiki/GNU_Core_Utilities
my norm is cat file | perl -p -e "s/.from ([0-9\.]+) ./\1/g" to get the ip out of the same datafile.
regex's seem to help with messy data or data that contains inconsistent delimiters.
(some of the stars got stripped by HN so the above won't work)
http://anyall.org/blog/2009/09/dont-mawk-awk-the-fastest-and...
Try putting a couple of spaces in front of your code line, like this:
See http://news.ycombinator.com/formatdocEdit: for simple regexes, sed works well, too, and probably loads slightly faster than perl.
Also, for programmers, I'd recommend ack over grep.
My MO these days is if it's anything more complicated than an awk one-liner like awk '{print $2 " " $NF}', I'll use Python or, lately, Ruby. (Perl would be fine, too, if I used it in other contexts often enough.)
That said, there's nothing quite like, well, programming your environment. The extent to which you can manipulate files, directories, and text in *nix right out of the box makes me feel privileged to understand it. I can remember a time when renaming a bunch of images en masse seemed tantalizing but out of reach. I've since learned quite a bit, and even though it's relatively mundane now, it still feels magical. Upthread, someone called it "moving mountains." That's precisely it, and I love it.
Yes, yes. I'm a complete and utter nerd, etc.