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I was wondering what does the <> do in a grep command
grep a b c, try to findain filebandcgrep <html> foo?
What does the <> do? Find the HTML tags?
ricedragon
Posted 2011-10-03T21:47:00.213
Reputation: 57
What does <html> do in a grep command?
Answers
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When inside quotes...
grep '<html>' foo
grep "<html>" foo
...it does exactly that: find a <html> tag inside the foo file.
grep and egrep use POSIX regular expressions, which are described in the manual page of regex(7) – basic for grep, extended/modern for egrep. Neither version treats < or > specially.
When not inside quotes, however, it doesn't do anything useful.
grep <html> foo
grep < html > foo
Most commonly used shells will treat the above equally: run command grep with no arguments, reading from file named html, writing to file named foo. But this won't work, because there is no "pattern" to be given to grep, so you'll get an error message (and an empty foo file).
user1686
Posted 2011-10-03T21:47:00.213
Reputation: 283 655
1Since ricedragon is new to regular expressions, it is worth pointing out that
grep '<html>' foowill not find<html lang="en">. It is often better to use an HTML parser for searching HTML. – RedGrittyBrick – 2011-10-04T09:14:05.283