问题
On Solaris, it appears I need to single quote 'a match the beginning of line' expression:
> sh
$ echo offset 0.000000 2>&1 | grep ^offset | tail -1
offset: not found
$ Usage: grep [-c|-l|-q] [-bhinsvwx] pattern_list [file ...]
grep [-c|-l|-q] [-bhinsvwx] [-e pattern_list]... [-f pattern_file]... [file...]
grep -E [-c|-l|-q] [-bhinsvx] pattern_list [file ...]
grep -E [-c|-l|-q] [-bhinsvx] [-e pattern_list]... [-f pattern_file]... [file...]
grep -F [-c|-l|-q] [-bhinsvx] pattern_list [file ...]
grep -F [-c|-l|-q] [-bhinsvx] [-e pattern_list]... [-f pattern_file]... [file...]
I can fix this easily enough by single quoting the regex:
> sh
$ echo offset 0.000000 2>&1 | grep '^offset'| tail -1
offset 0.000000
I don't see this in my own command line where I'm using bash, but it shows up in scripts, such as a perl script that uses system().
Is that default Solaris shell the Bourne shell? What additional meaning does ^ (caret) have in the shell language for the default Solaris shell?
回答1:
I believe '^' in bourne shell was allowed as a backwards compatible version/equivalent of the '|' char.
And the message that your seeing would seems to support that interpretation.
To confirm, make a test script offset that just prints 'got to offset' to see.
(Backwards compatible to what is lost in this ol' SunOS3 coder's /dev/null ;-) )
IHTH.
来源：https://stackoverflow.com/questions/13125406/special-meaning-of-caret-in-solaris-bourne-sh