Path: csiph.com!weretis.net!feeder6.news.weretis.net!nntp.club.cc.cmu.edu!micro-heart-of-gold.mit.edu!bloom-beacon.mit.edu!bloom-beacon.mit.edu!171.64.64.130.MISMATCH!usenet.stanford.edu!not-for-mail From: Chet Ramey Newsgroups: gnu.bash.bug Subject: Re: Unset array doesn't work Date: Tue, 27 Feb 2018 11:18:40 -0500 Lines: 53 Approved: bug-bash@gnu.org Message-ID: References: <790ade74-690f-541c-9ab4-6359917442d0@case.edu> <755d61fa-d2bc-8855-bc30-4388aff40691@gmail.com> <9974.1519637469@jinx.noi.kre.to> 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 1519748342 14292 208.118.235.17 (27 Feb 2018 16:19:02 GMT) X-Complaints-To: action@cs.stanford.edu Cc: chet.ramey@case.edu, bug-bash@gnu.org To: Robert Elz Envelope-to: bug-bash@gnu.org User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 In-Reply-To: <9974.1519637469@jinx.noi.kre.to> Content-Language: en-US X-Junkmail-Status: score=8/60, host=mpv3-2015.case.edu X-Junkmail-PrAS-Raw: score=8/60, refid=2.7.2:2018.2.27.154517:17:8.317, ip=, rules=__HAS_REPLYTO, __HAS_CC_HDR, __MULTIPLE_RCPTS_CC_X2, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __SUBJ_ALPHA_END, __TO_MALFORMED_2, __TO_NAME, __TO_NAME_DIFF_FROM_ACC, __REFERENCES, __HAS_FROM, FROM_EDU_TLD, __HAS_MSGID, __SANE_MSGID, DATE_TZ_NA, __USER_AGENT, __MOZILLA_USER_AGENT, __MIME_VERSION, __IN_REP_TO, __CT, __CT_TEXT_PLAIN, __CTE, __REPLYTO_SAMEAS_FROM_ADDY, __REPLYTO_SAMEAS_FROM_ACC, __FROM_DOMAIN_IN_ANY_CC2, __REPLYTO_SAMEAS_FROM_DOMAIN, __ANY_URI, __URI_WITH_PATH, __URI_NO_WWW, __STOCK_PHRASE_24, __CP_NAME_BODY, __CP_URI_IN_BODY, __FRAUD_MONEY_CURRENCY_DOLLAR, __SUBJ_ALPHA_NEGATE, __URI_IN_BODY, __URI_NOT_IMG, __FORWARDED_MSG, __NO_HTML_TAG_RAW, BODY_SIZE_1500_1599, BODYTEXTP_SIZE_3000_LESS, __MIME_TEXT_P1, __MIME_TEXT_ONLY, __URI_NS, HTML_00_01, HTML_00_10, __FRAUD_MONEY_CURRENCY, BODY_SIZE_5000_LESS, IN_REP_TO, MSG_THREAD, [TRUNCATED], so=2010-03-03 19:42:08, dmn=2016-08-03-0138 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4.x-2.6.x [generic] [fuzzy] X-Received-From: 129.22.103.194 X-BeenThere: bug-bash@gnu.org X-Mailman-Version: 2.1.21 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:13758 On 2/26/18 4:31 AM, Robert Elz wrote: > Date: Mon, 12 Feb 2018 09:26:37 -0500 > From: Chet Ramey > Message-ID: <790ade74-690f-541c-9ab4-6359917442d0@case.edu> > > | This is bash's dynamic scoping. The visibility of a local variable is > | restricted to a function and its children, and `unset' removes the > | currently-visible instance. Removing such an instance can `unconver' an > | instance in a previous scope. > > Frankly this is brain dead, unset should not be unlocal (or something equiv) > > eg: if I have a func > > myfunc() { > local IFS > unset IFS > # do some code > } > > the very last thing that I want is for the global IFS to apply. It doesn't. Run the following script: func() { local var=$'a\tb\tc' typeset IFS=' ' echo ${FUNCNAME}: before unset: $var unset IFS echo ${IFS:-null or unset} echo ${FUNCNAME}: after unset: $var } IFS='%' declare -p IFS func declare -p IFS You'll see that the first expansion of `$var' uses the local value of IFS, the second expansion uses the default value of $' \t\n', and the global value doesn't change (or get unset) outside the function. The objection was that the global or previous-scope value didn't get unset when using the `unset' builtin; only in the local scope was it unset. -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, UTech, CWRU chet@case.edu http://tiswww.cwru.edu/~chet/