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[174.130.73.160]) by smtp.gmail.com with ESMTPSA id w206sm3984142ywc.51.2019.08.20.17.38.26 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Aug 2019 17:38:27 -0700 (PDT) To: Adam Thornton , The Eunuchs Hysterical Society References: From: Chet Ramey Openpgp: preference=signencrypt Autocrypt: addr=chet.ramey@case.edu; prefer-encrypt=mutual; keydata= mQGiBEEOsGwRBACFa0A1oa71HSZLWxAx0svXzhOZNQZOzqHmSuGOG92jIpQpr8DpvgRh40Yp AwdcXb8QG1J5yGAKeevNE1zCFaA725vGSdHUyypHouV0xoWwukYO6qlyyX+2BZU+okBUqoWQ koWxiYaCSfzB2Ln7pmdys1fJhcgBKf3VjWCjd2XJTwCgoFJOwyBFJdugjfwjSoRSwDOIMf0D /iQKqlWhIO1LGpMrGX0il0/x4zj0NAcSwAk7LaPZbN4UPjn5pqGEHBlf1+xDDQCkAoZ/VqES GZragl4VqJfxBr29Ag0UDvNbUbXoxQsARdero1M8GiAIRc50hj7HXFoERwenbNDJL86GPLAQ OTGOCa4W2o29nFfFjQrsrrYHzVtyA/9oyKvTeEMJ7NA3VJdWcmn7gOu0FxEmSNhSoV1T4vP2 1Wf7f5niCCRKQLNyUy0wEApQi4tSysdz+AbgAc0b/bHYVzIf2uO2lIEZQNNt+3g2bmXgloWm W5fsm/di50Gm1l1Na63d3RZ00SeFQos6WEwLUHEB0yp6KXluXLLIZitEJLQwQ2hldCBSYW1l eSAoQ2FzZSBzdGFuZGFyZCkgPGNoZXQucmFtZXlAY2FzZS5lZHU+iF8EExECAB8FAkPi19EC GwMHCwkIBwMCAQMVAgMDFgIBAh4BAheAAAoJELtYafBk6nSrelkAn31Gsuib7GcCZHbv5L5t VKYR9LklAJ4hzUHKA49Z0QXR+qCb80osIcmPSbkBDQRBDrBvEAQAkK6TAOKBEM+EC4j6V/7o /riVZqcgU5cid2qG9TXdwNtD9a3kvA/ObZBO93sX59wc6Bnwo4VJxsOmMlpGrAjJsxNwg3QH akEtf8LXRbVpj5xStdmBdQZUhIQyalo/2/TZq5OijtddUQcL5cs70hTv/FpT3wUvr2Xr8rjF 41IFEz8AAwcD/A0CZEGlzIrT5WCBnl6xBog/8vKiUCbarByat3d1mL6DbizvKNXQRTC9E/vE dENAWCQCjr75Bu55xT8n3SXGtWdDC5xmZ/P3OBYORP8yl8H8I1FIosWOFirbIeYdZPq8SPD1 HL+EXo9zSiHVrrZRJ19ooCKKbSdXHFCY+aJG+0KZiEkEGBECAAkFAkEOsG8CGwwACgkQu1hp 8GTqdKvjcACfZlkVCDwaz/NTO9cy3t69oWpVPNwAnRwe0qk/WL/gfhH346xh5B3HFbFN Organization: ITS, Case Western Reserve University Message-ID: <83aa800b-76e8-7d72-8f1b-2148e36eec05@case.edu> Date: Tue, 20 Aug 2019 20:38:08 -0400 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Junkmail-Status: score=9/90, host=mpv4-2015.case.edu X-Junkmail-PrAS-Raw: score=9/90, refid=2.7.2:2019.8.20.231816:17:9.975, ip=, rules=__YOUTUBE_RCVD, DKIM_SIGNATURE, __X_GOOGLE_DKIM_SIGNATURE, __HAS_REPLYTO, __HAS_CC_HDR, __SUBJ_REPLY, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __SUBJ_ALPHA_END, __TO_MALFORMED_2, __TO_NAME, __TO_NAME_DIFF_FROM_ACC, __HAS_REFERENCES, __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, __TO_IN_SUBJECT2, __REPLYTO_SAMEAS_FROM_DOMAIN, __DKIM_ALIGNS_1, __DKIM_ALIGNS_2, __ANY_URI, __URI_WITH_PATH, __URI_NO_WWW, __CP_NAME_BODY, __CP_URI_IN_BODY, __SUBJ_ALPHA_NEGATE, __URI_IN_BODY, __URI_NOT_IMG, __FORWARDED_MSG, __BODY_NO_MAILTO, __NO_HTML_TAG_RAW, BODYTEXTP_SIZE_3000_LESS, BODY_SIZE_900_999, __MIME_TEXT_P1, [TRUNCATED], so=2010-03-03 19:42:08, dmn=2016-08-03-0138 Subject: Re: [TUHS] Shell builtin exec X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: chet.ramey@case.edu Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On 8/20/19 5:10 PM, Adam Thornton wrote: > This is probably the place to ask: > > I understand why the shell builtin "exec" is the same as the syscall exec() > in the sense of "replace this process with that one."  But why is it also > the way to redirect filehandles in the current shell?  (That is, why isn't > the redirection named something else?) It was probably a side effect that turned out to be useful. The `exec' builtin performs redirections without a way to undo them, because why bother, and executes its arguments as a command with arguments, as if it were in a child process. The original Bourne shell just performed the redirections and returned if there weren't any arguments, leaving the non-undoable redirections in place. -- ``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/