Puppy Linux Discussion Forum

[aragon]

for a little menu-project, i need to substitute " " with "-" ... but only some ...

here is an example line

[jemimah]

[jemimah]

I tried really hard for a one liner, but I can't figure it out, so here's the boring way.

[2byte]

[amigo]

bash baby! don't need all those external calls. If you run this looped a few hundred times, you'll see a big speed difference by just using what the shell can do.

[jemimah]

Yeah I figured there was some Bash voodoo like that you could do. Can you recommend a good (fun!) bash programming book?

[amigo]

No, I don't really know of a fun book or manual. There is, of course, the bash advanced scripting guide:
http://tldp.org/LDP/abs/html/

I do nearly everything in bash, but I don't even touch any of the really advanced techniques, even though they would save lines or make even more possible.

You might like to look and learn from some examples I have done as a hobby. I have put together pure-bash clones of over a dozen command-line utilities -even a version of wget. Most of them follow a common methodology and syntax, so studying them gets easier as you go along. You can find them here:
http://distro.ibiblio.org/pub/linux/distributions/amigolinux/download/AmigoProjects/BashTrix/

To explain what I did above:
PART1=${STRING%% \"*}
separates what is to the left of ' "' (space+double-quote)
PART2=${STRING#*\"}
separates what is to the right of the first '"'

To illustrate this a little better, use a longer string which includes more than one quoted word, and then try various combinations using one '#' or two '#' chars, and one '%' or two '%' chars
Using one of either % or # means the shortest match, using two mean the longest match.
This:
echo ${PART1// /-}
substitutes the spaces with '-' chars. If you do this:
echo ${PART1/ /-} \"$PART2
it only substitutes the first occurrence(using the double'//' makes it act like the sed 'g' (global) option.
The double-quote chars always have to be escaped.

I dislike using regex's because it makes my head spin to try and read them. I used to use cut, grep and rev a lot, but mostly I do it with bash these days, even though it takes more lines to do the same thing. BTW, 'case' statements can be used to substitute for grep to nice effect.

[jemimah]

Thanks! This will be helpful.

[Lobster]

[technosaurus]

[aragon]

girls and guys,

this is why i love this forum, you're not only getting an answer, no you have the possibility to learn something.

thank you all.

aragon