As long as you’re doing lots of work in Linux, there are some more things you’ll want to get used to. I spent a lot of time in the command line. (It’s kind of hard to avoid when you’re working on a headless server.) These tips are useless if you don’t have a basic familiarity, but for people with a relatively basic knowledge, here are tips that might come in handy:<\/p>\n
Very often in less<\/strong>, I want to jump to the end<\/em> of a file and work my way up. I can hit space over and over. One day I thought I was clever, when I realized it would tell you how many lines were in the file, and I began telling it jump to line 123 by typing :123 within less. But it turns out it’s even easier. G takes you to the last line. g takes you to the first line. There are many more handy tips here<\/a>.<\/p>\n Of course, I spent even more time in vi<\/strong>. Search and replace<\/a> is handy. But keep in mind that the :s\/old\/new command will only work on one occurrence. You can append a g, ending up with :s\/old\/new\/g, but it’s only going to work on one line. This is usually not desirable. You can specify a line range. Generally, though, you want the whole file. $ denotes the end of the file, so you can do it as “1,$,” denoting “From line 1 to the end of the file.” But it’s even easier: % means “the whole file.” So I end up with…. :%s\/old\/new\/g to replace all “old” with “new”. And if this isn’t what you want, press u to undo. The “G” trick to jump to the end works in vi, too. Turns out you can replace :wq with ZZ, which is essentially <\/em>the same<\/a>.<\/p>\n I’ve known about the uniq<\/strong> command for quite some time: its goal is to weed out duplicate lines. This is handy far more often than you might imagine: say you strung a ton of commands together to pull out a list of all e-mail addresses that your mailserver has rejected. There are bound to be many, many duplicates, because apparently bumttwagnerfor@domain is commonly-spammed (?!).<\/p>\n But uniq has a peculiar quirk that I missed. They call it a feature, although I’m not sure I agree. It’s for filtering out sequential<\/em> duplicate lines. If the duplicate lines aren’t in order, it will merrily pass them on. I suppose there may be scenarios when this is desirable, although I’m at a loss to think of any. In a nutshell, whenever you want uniq<\/strong>, you probably want to run it through sort <\/strong>first. grep something \/var\/log\/messages | sort | uniq<\/tt>, for example, will pull out all lines with “something” in them, but omit all <\/em>duplicates.<\/p>\n And note that use of grep<\/tt>. For some reason people seem to think that echo filename | grep search_pattern<\/tt> is the way to do it… There’s no reason for echo<\/tt>. Just do grep search_pattern filename<\/tt>.<\/p>","protected":false},"excerpt":{"rendered":" As long as you’re doing lots of work in Linux, there are some more things you’ll want to get used to. I spent a lot of time in the command line. (It’s kind of hard to avoid when you’re working … Continue reading