I am got a regular expression in sed, I am not sure ":" stand for anything here.

sed 's/:[^\t]*//g'

Could you please give me some infomation?

Update: I got the command from a publication, I'm confused because if the : is a normal character, then the [^\t] following it means the start of the line, which seems to actually match a : before the start of the line, which doesn't seem to have any effect?

Best.

Zhang.

CodePudding user response：

I'm confused because if the : is a normal character, then the [^\t] following it means the start of the line, which seems to actually match a : before the start of the line, which doesn't seem to have any effect?

Normally, ^ means "start of line", that's right.

However, what you're looking at here is a character set. And in that context, the ^ means "negated".

So actually, [^\t] has got nothing at all do do with "start of line". It means "not a tab". (\t means "tab character".)

In summary, this regex:

:[^\t]*

means "a literal : character, followed by any number of non-tab characters".

CodePudding user response：

There is nothing special about : in regex. It simply matches a : character.

All special characters are listed in the documentation (that's Python since you tagged with python-re; the dialect used by sed is different but also doesn't have a special meaning for :).