Path: csiph.com!xmission!news.snarked.org!news.linkpendium.com!news.linkpendium.com!panix!usenet.stanford.edu!not-for-mail From: Chet Ramey Newsgroups: gnu.bash.bug Subject: Re: Empty ""s in ARG in ${x:+ARG} expand to no words instead of the empty word if prepended/appended with space Date: Sat, 21 Jul 2018 11:33:18 -0400 Organization: ITS, Case Western Reserve University Lines: 25 Approved: bug-bash@gnu.org Message-ID: References: <3d5b8d4b-b77e-2486-b45b-ca733e4d0ca0@redhat.com> <20180720223753294160030@bob.proulx.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 1532187210 1838 208.118.235.17 (21 Jul 2018 15:33:30 GMT) X-Complaints-To: action@cs.stanford.edu Cc: chet.ramey@case.edu To: bug-bash@gnu.org Envelope-to: bug-bash@gnu.org X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:cc:subject:to:references:from :organization:message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=3n3cXCy+1fRhvMhIZbNe4k3vraLEhx+QEjaMF37cids=; b=LkKl7U3oZq1thdERqacfVolqq1VsA2YYMSHk5od+uQtcPatOFS/9KSAzcIQ/+uf/5p USr4n70xgGwaz2t7pD6WtPV7rBqkZbgxTNZS22+9F5stRpJzQiJKPIWbPFWw98IFtWiI i4hMmurNg2VnKFk+Zx3s9LyvdT7kxznP8fDvzzrc4LP8NL/iYE1HwQVFVPYB5VhQfijx iUQH2L4Z0zQ2uczng6APKMp/eAqUbwaJ7LMqsSZd0uygNj8rIVTmYBz7yCqqOT2cQ9M6 qamle19ebCBl+mD2hFMr4RB5BaR/T3O4Ryz6KP5ky681nd9X3/PzoYFLuLqrYWwDFAkH 9boQ== X-Gm-Message-State: AOUpUlHBcYZeIeuYJe4Cx4tSXZ9BKiH3kHxwR41hQv3EkOv6CgqDRFYE d4Hgvv35QDNcbq1Z3rJz66/A5XqQ+zygD1IOpc5OQ1mhn1eAss/S+eguXEGmr+3biezGj6Hfjd1 F2a5Ykb4xjR8= X-Received: by 2002:a6b:c5c6:: with SMTP id v189-v6mr4876094iof.167.1532187201125; Sat, 21 Jul 2018 08:33:21 -0700 (PDT) X-Google-Smtp-Source: AAOMgpfWvxxr4nd4B84AI2DrS0GUQKwMHcQJRWYMjpEyUiQBvvyeQkjAWvjA1gCd/MQBVljZoQ5kpw== X-Received: by 2002:a6b:c5c6:: with SMTP id v189-v6mr4876083iof.167.1532187200928; Sat, 21 Jul 2018 08:33:20 -0700 (PDT) User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 In-Reply-To: <20180720223753294160030@bob.proulx.com> Content-Language: en-US X-Junkmail-Status: score=7/90, host=mpv2-2015.case.edu X-Junkmail-PrAS-Raw: score=7/90, refid=2.7.2:2018.7.21.150316:17:7.944, ip=, rules=__YOUTUBE_RCVD, __HAS_REPLYTO, __HAS_CC_HDR, __SUBJ_REPLY, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __SUBJ_ALPHA_END, __TO_MALFORMED_2, __TO_NO_NAME, __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_CC1, __FROM_DOMAIN_IN_ANY_CC2, __REPLYTO_SAMEAS_FROM_DOMAIN, __ANY_URI, __URI_WITH_PATH, __URI_NO_WWW, __CP_URI_IN_BODY, __FRAUD_MONEY_CURRENCY_DOLLAR, __SUBJ_ALPHA_NEGATE, __URI_IN_BODY, __URI_NOT_IMG, __FORWARDED_MSG, __NO_HTML_TAG_RAW, BODYTEXTP_SIZE_3000_LESS, BODY_SIZE_900_999, __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, __FROM_DOMAIN_IN_RCPT, [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: 129.22.103.227 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:14378 On 7/21/18 12:44 AM, Bob Proulx wrote: > Denys Vlasenko wrote: >> $ f() { for i; do echo "|$i|"; done; } >> $ x=x >> $ e= >> $ f ${x:+ ""} >> ^^^^^^^^^^^ prints nothing, bug? >> >> $ ${x:+"" } >> ^^^^^^^^^^^ prints nothing, bug? > > Insufficient quoting. That argument should be quoted to avoid the > whitespace getting stripped. (Is that during word splitting phase > using the IFS? I think so.) Even if the whitespace gets stripped out, the quoted null string should result in an empty argument. Different shells are inconsistent about this, but I believe that if word splitting occurs, the empty string (or "$e", anything that expands to an empty string) should result in a null word. -- ``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/