Exclamation points in quoted strings
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi, I'm not a shell script pro and I don't know much about POSIX, but I have found this puzzling behavior in bash, and although it is documented I don't really understand why bash behaves this way. I was hoping someone could tell me. [EMAIL PROTECTED]:~$ set -H [EMAIL PROTECTED]:~$ echo "hi!" bash: !": event not found [EMAIL PROTECTED]:~$ echo "hi\!" hi\! This is somewhat unusual; generally, characters protected by backslashes are put through *unescaped*. Compare: [EMAIL PROTECTED]:~$ echo "\`" ` [EMAIL PROTECTED]:~$ echo "\"" " [EMAIL PROTECTED]:~$ echo "hi\$" hi$ The manual page does say explicitly, under "Quoting": The backslash preceding the ! is not removed. But no explanation is given for why this behavior exists. Is it part of POSIX compliance? An implementation detail? Ethan -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHEDFMhRlgoLPrRPwRAmj1AJ9Ch7mz87lP/NRm+8+ZqXUOULk1sACgh2Kw 1ArDcXwqPrDZOdWoz038t1E= =7fHW -END PGP SIGNATURE-
Re: Exclamation points in quoted strings
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Chet Ramey wrote: > Not true, in general. Posix specifies the characters the backslash > can escape in double-quoted strings. You happened to choose three of > the five. > > http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02 > _02_01 > > The backslash shall retain its special meaning as an escape character > (see Escape Character (Backslash)) only when followed by one of the > following characters when considered special: > > $ ` " \ I think I see. So the backslash isn't counting as an escape character here, and so passes through without being removed, but does inhibit history expansion anyhow? Thanks a lot! I still think the behavior is confusing, but at least I know why it happens. Ethan -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHEtfChRlgoLPrRPwRAkonAKCsGDABs+TXOya432vkIc5z4ApEXgCg2fH9 vwlDCQgES6KEJ7jxdLHetYM= =3FLD -END PGP SIGNATURE-
