Path: csiph.com!optima2.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!usenet.stanford.edu!not-for-mail From: Chet Ramey Newsgroups: gnu.bash.bug Subject: Re: Enhancement: bash should have uniform escape syntaxes for `echo -e`, `printf` and `$'ANSI_C_style_escape'`. Date: Mon, 10 Aug 2015 16:56:52 -0400 Lines: 35 Approved: bug-bash@gnu.org Message-ID: References: <523431b6.2c9.14f18e12b67.Coremail.arthur200126@163.com> Reply-To: chet.ramey@case.edu NNTP-Posting-Host: lists.gnu.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Trace: usenet.stanford.edu 1439240228 24658 208.118.235.17 (10 Aug 2015 20:57:08 GMT) X-Complaints-To: action@cs.stanford.edu Cc: chet.ramey@case.edu To: Arthur200000 , "bug-bash@gnu.org" Envelope-to: bug-bash@gnu.org X-Enigmail-Draft-Status: N1110 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0) Gecko/20100101 Thunderbird/38.0.1 In-Reply-To: <523431b6.2c9.14f18e12b67.Coremail.arthur200126@163.com> X-Junkmail-Status: score=10/50, host=mpv5.cwru.edu X-Junkmail-Whitelist: YES (by domain whitelist at mpv2.tis.cwru.edu) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4.x-2.6.x [generic] X-Received-From: 129.22.105.37 X-BeenThere: bug-bash@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Bug reports for the GNU Bourne Again SHell List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Xref: csiph.com gnu.bash.bug:11319 On 8/10/15 2:30 PM, Arthur200000 wrote: > Bash Version: 4.3 > Patch Level: 30 > Release Status: release > > Description: > Bash has different escape syntaxes for `echo -e`, `printf` and `$'ANSI_C_style_escape'`. Take a specific point, `printf` and `$'C_Style'` accepts octals not starting with 0, but `echo -e` doesn't. > This is causing quite a lot of confusion. They are different because they are supposed to be different according to the relevant standards. echo -e and the xpg_echo shell option expand the escape sequences that Posix specifies: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/echo.html#tag_20_37 with the addition of \e, \E, and \xHH. Posix requires the leading 0. printf expands the escape sequences that Posix specifies: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/printf.html#tag_20_94 (note that printf %b is supposed to behave like echo) The $'...' string expansion behaves like ANSI-C, which just uses one to three octal digits for octal numbers. It adds support for \e and \E, as well as \c. There is a proposal to add this to the next version of Posix which retains this behavior. (And as for Apple's bash-3.2, they modified bash to behave as it does. Bash-3.2 as distributed understands \e in the echo format string.) -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, ITS, CWRU chet@case.edu http://cnswww.cns.cwru.edu/~chet/