grep

grep [options] PATTERN [FILE...]
grep [options] [-e PATTERN | -f FILE] [FILE...]

printenv <html>	</html> grep lib	print a list of environment variables that contain “lib”
grep -e foo -R -n .	search from current directory and below, inside of files for “foo”, and print a list of file paths, line numbers, and lines that match
grep -e foo -R -l .	search from current directory and below, inside of files for “foo”, and only print a list of files that match
grep -i foo -R -l .	same as previous, but case insensitive “foo” (foo, Foo, FOO, etc…)

find all todo's and fixme's, ignoring case, from this directory and deeper, ignoring any results with .svn or .log
```
grep -R -n -iE 'todo|fixme' . | grep -v -E '\.svn|\.log'
```

search all files in this directory and lower, finding carriage returns (\r, ^M)

grep -U -R -P '\x0d' *
or list files only (this example uses octal carriage return)
grep -U -R -l -P '\015' *

Command line usage