Shell Programming and Scripting

This got very interesting actually. I was quite surprised to see that sed considered '|' as literal '|' and not any operator.

In that case, why it did not consider '[ ]' literally in my earlier reply #9? Consider the following for example

echo "acb" | sed 's/[cC]/z/'

and

echo "aCb" | sed 's/[cC]/z/'

Both give the same output as

azb

Well, I am really thankful to you for all your replies and hope I am not bugging anyone by not putting an end to this.

that is how you group to form regex with '[' and ']'

if it all those needs to be treated above literally,

Code:

echo "a[b" | sed 's/\[/h/'

You don't "or" that way for commands -

Code:

sed 's/^[ \t]*//;s/[ \t]*$//'

The snippet above trims leading blanks ; then trims trailing blanks

Note the ; which acts to separate actions

In your case you'd need several ; delimited commands - one for each possible substitution.

Thanks Jim and all

I guess I got my answer. Jim put it down nicely by saying 'you dont use "or" in commands like that'

Thanks all for your replies...