UNIX for Dummies Questions & Answers

I'm goin to drive crazy soon, if i can not do this. I have a text file (570kb) and i have to replace the apostrophe " ' " and minus "-" with space " ". i have done it for minus:

sed 's/-/ /g' aaa.txt >zzz.txt

this replaced minus with space.

but i can not use the same command for ' .

sed 's/'/ /g' aaa.txt >zzz.txt

does not work, i need help, i think

Yo try this:

Code:

sed s/"'"/" "/g aaa.txt >zzz.txt

I just learnt something!

oh my gosh! i really learnt something new! i have googled 2 days, found nothin' .
but can you explain why, if possible?

thx dan-e

.... haha I'm only reading this forum so that I can learn more myself, but I came across a similar example in a hardcopy book called "Sed & Awk" (O'reilly). According to the book you don't need to enclose your sed argument with quotes (as you have in this example - single quotes), and I'm sure this is what was breaking your statement.

I tried a few things myself and decided it was the outside quotes breaking things, and then found out you can enclose your pattern and substitution string with double quotes (not sure if singles work too). Gave it a shot and it worked.

The reason that your example fails is because these such commands rely on 'delimeter' characters to break up their data. Eg. for a program to read a string it finds the next quote - " - and then starts grabbing anything after the quote until it hits another quote - " - and then says 'everything in-between is the string'. Of course this doesn't work if the string itself contains a quote, like in your example. To get around this problem, they invented 'escape' characters which say to the program 'hey don't worry about this quote - it's part of the string' Eg:
1. "A string" = A string
2. "A string with \"escape characters\"" = A string with "escape characters"
3. "A broken string without "escape characters"" = A broken string without

Your example falls into category 3. However, I couldn't find a way to use an escape character with the single-quote. I would have thought that this would work:

Code:

sed 's/\'/ /g' aaa.txt >zzz.txt

- Note the \ escape character preceding the single-quote. But this doesn't work. I don't know why, if people would program like me it would work. But they don't. Which is why bad software exists. And microsoft.

oh, i think i need to buy some more books thx dan-e for the whole information.