Vim’s powerful navigation

I was reading about the Mac OSX Terminal app and somebody complained about vim being slow. A vim programmer shed some light on how to use vim’s amazing keyboard navigation:

Using Vim in Terminal.app, I can easily scroll about 5100 lines in 10 seconds, using ctrl-F or ctrl-B (scroll one page forward or back), if you’re trying to move a long distance in a hurry. I get the same speed in MacVim (which can update the screen much faster than Terminal.app), so I’m pretty certain that the limiting factor (at least in MacVim) is the keyboard repeat rate, not Vim’s ability to update the screen.

The only way I get roughly 120 lines in 10 seconds, is scrolling Vim (or MacVim) line-at-a-time by holding down “j” or the down arrow, and that’s clearly the default keyboard repeat rate (about 12 per second) limiting things.

You can easily adjust the keyboard repeat rate in System Preferences, in the Keyboard pane, by fiddling with “Key Repeat Rate” and “Delay Until Repeat”. But I’ve been using Vi/Vim/MacVim for a loooong time, and have never felt the need to have the keyboard repeat faster; the key (no pun intended) is to use Vim as it was intended…

If you want to move 3 lines down (or up) hit “j” (or “k”) 3 times (much faster than waiting for key repeat to kick in). If you want to move 10 or 20 lines down, then maybe hold down “j” (“k”) and let it repeat. But if you want to go further, that’s the wrong way: ctrl-D (ctrl-U) will take you half a screen Down (Up), ctrl-F (ctrl-B) will take you a full screen Forward/down (Back/up)… holding any of these down will get you somewhere fast. If you’re trying to get to somewhere in particular: “]]” (“[[“) will jump forward (backward) to the start of the next (previous) function (in C/Obj-C/Perl/Java/Javascript or any other language where “{” by itself at the start of a line indicates the start of a function), or use “/” (“?”) to search for some text and “n” to jump to subsequent occurrences until you reach the right one. Or use tags (see “:help tags”), build a tags file for your code, then you can use “:tag yourfunctionname” to jump to a function definition in any file, or sit on the function’s name in a call somewhere and hit ctrl-] to jump to the definition (and ctrl-T to jump back to the call). Or even more lazily, in Vim, if you sit on any identifier and hit “*” (“#”), Vim will select that identifier as search text and take you to the next (previous) occurrence, where you can use “n” to keep searching further — this is more than sufficient in smaller files. And turn on incremental searching and search highlighting (“:set incsearch hlsearch”, worth putting in your ~/.vimrc), then the search results will be more obvious on the screen.

Finally, nearly everything in Vim (and Vi before it) takes a repeat count argument. If what you want is really to jump 179 lines down, then type “179j” (and if you wanted to get to line 423, that’s “423G”). Use the full power of Vim as it was intended, and keyboard repeat rate will never be a limiting factor.

And if you’re using Vim on the Mac extensively, you owe it to yourself to check out MacVim — you can still start it from Terminal.app (an included helper script lets you type “mvim file1 [ file2… ]” at a command line prompt), but it’s much more Mac-like — cut’n’paste and drag’n’drop interact well with other programs, you get real scroll bars (drag those to move through a file really quickly), multiple editing windows, and you can use the mouse for selecting text, along with (practically) unlimited colors for color syntax highlighting (you do use that, right? “:help syntax” or just “:syn on” to switch it on), instead of the 16 colors you’re limited to in Terminal.app. And it’s fast.

Vim (and MacVim) is the ultimate programmer’s editor, if you take the time to really learn how to use it — it requires the smallest amount of hand movement to make changes (especially since one never has to reach for the mouse), it’s insanely customizable/programmable, and it has a very smartly laid out command set — yes, it has a steep learning curve, but for something that I use 10 hours a day, I’ll take easy/powerful to use over easy to learn any day.

Cheers,
Carl

Source: MacRumors

Mplayer’s useless warnings at startup

Installed an mplayer rpm from RPMForge repository (mplayer.i386 1.0-0.40.svn20090711.el5.rf) to my CentOS 5 server. I was setting up a bash script to decode and encode several media files. Everytime mplayer was called from the script, I would get the following useless warnings:

MPlayer SVN-r29417-4.1.2 (C) 2000-2009 MPlayer Team
Can't open joystick device /dev/input/js0: No such file or directory
Can't init input joystick
mplayer: could not connect to socket
mplayer: No such file or directory
Failed to open LIRC support. You will not be able to use your remote control.

It was building up my logs. So I put the following two lines in my mplayer configuration file at /etc/mplayer/mplayer.conf:
nolirc=yes
nojoystick=yes

And like linux magic, the errors on each load disappear.

Helpful Linux Tips

Command line

Download all specified extension files from an html page:

wget -r -t1 -N -np -A.mp3 http://google.com/music/audio/

-np dont ascend to parent
-r recursive
-l1 level DONT NEED
-N timestamping
-nd no directories DONT NEED
-t 1 = tries
-H span across hosts

To remove quotas, edit /etc/fstab and remove grpquota,usrquota,
then execute the remount, replacing /home with the name:

mount -o remount /home

Convert unix timestamp to readable format in Bash

date -d @1280565192

Kill multiple processes using grep:

kill -9 `ps aux | grep perl | grep nobody | awk '{print $2}'`

Xargs: handle spaces and punctuation properly:

xargs -0

Using ack and sed, edit files in place

sed -i 's/replacestring/replacedwiththis/g' `~/bin/ack --php "searchstring" -l`

Rename doesn’t support renaming with a dash/hyphen, so we must use this forloop/mv hack:

for i in ./*foo*;do mv -- "$i" "${i//test test2/test - test2}";done

Find Command

COPY files less than 24 hours old to /some/other/directory

find . -type f -ctime -1 | xargs -I {} cp {} /some/other/directory

MOVE files less than 24 hours old to /some/other/directory

find . -type f -ctime -1 | xargs -I {} mv {} /some/other/directory

Scan files for certain text

find dir/ -name "*.txt" -exec grep -Hn "md5_func" {} \;

Find all directories and sub-directories that are empty.

find ./ -type d -empty

MySQL

Using mysql from command line, here’s how to save results to an outfile (in interactive mode):

SELECT * INTO outfile '/tmp/sql.out' FROM tablename WHERE condition  = '1';

Using mysql from command line, here’s how to save resultset to an outfile (using a sql file):

mysql database -u username -p < batch.sql > sql.out