From owner-freebsd-hackers@freebsd.org Mon Aug 19 17:10:07 2019 Return-Path: Delivered-To: freebsd-hackers@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 4157BCBC1D for ; Mon, 19 Aug 2019 17:10:07 +0000 (UTC) (envelope-from luthramihir708@gmail.com) Received: from mail-ua1-x944.google.com (mail-ua1-x944.google.com [IPv6:2607:f8b0:4864:20::944]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46C0mG1X5Kz43D2 for ; Mon, 19 Aug 2019 17:10:05 +0000 (UTC) (envelope-from luthramihir708@gmail.com) Received: by mail-ua1-x944.google.com with SMTP id y7so911211uae.10 for ; Mon, 19 Aug 2019 10:10:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=Rb+F02UKxpgz3UxcVvfj7GvkMkR9iXoro03B97qLaWY=; b=Fn48+bplWcFZ5yyKXnsvSaIfUzeyIl1NrfElnD1i6NwoUaY6wo0iC4r/phWnZ/ykjm B6I6Kq+DA/4ga+KZ3FCgpbuLBph079/3dWqvty8Ez64jdLykSRIpADRpGVfhGEMYw35q SQ6aBePQ7Mlrlyno9+xMqoUPH5P1n4NJlGWgEEmedmAXg7KQahZ2yMyVlcChoWbhXGEh iCddOHMc7pP9ZglI4aQtDvo+O2bXsE+O8BoshnfeTtJepLALOG2geZDU68y+mi8E7nX9 cvpvh2YHMHlHeElrHy6bte+1bELWNnMGULZmUX/kIo1VbgMQGiaVfZlaCCfvtUrZGToY 5h9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=Rb+F02UKxpgz3UxcVvfj7GvkMkR9iXoro03B97qLaWY=; b=NH9q2IwHOLZjeDJvxUgKZi9X2kh9cz0xt8pT5GZKSv1FURn+xkp97zMoiBRQM2Fz0K X6kkKFhHwW5Wtmf4yzVIiCn+Hcun6xhIZIRx1e+kvr0oHm+qguRF0qj/Q4+r9En5k4qt qNeomKIPYfRmN7O0/qI2yJQYakQnKH4HlCqARGi9eNzXQdf9Bb96S8qhKl/ecAr68Wfb Z2g1Vd5WfGwUq//eULIxipPon5FNp06WuQ6DQelCv+A2qeIWdUl/sc2eVPGXIgwyKHn4 HKSpDsOHIOx+ZL5EiD7IvdIpZA9EmwvZOOQi+6QrheGffaosC6KjCKOOMIpM9lq/G35S 2x4Q== X-Gm-Message-State: APjAAAVhQKfJW4qKcwi0pRIO3pnD0lA9Vw6cynnGzQeMHoi2UL7oSQ2b QUHPzC0GuIA2jON3E46tT6fQi7LmTSjcD95h8Ar9OwDf X-Google-Smtp-Source: APXvYqw0v9XrEUrosQglvCCvbRM6VoRrii2fsnE84GJr22YJ/YirERPr0WMYrV+r07KC1RSykCy2rQOtAK5rKWHr/Rs= X-Received: by 2002:ab0:1573:: with SMTP id p48mr1859409uae.78.1566234604376; Mon, 19 Aug 2019 10:10:04 -0700 (PDT) MIME-Version: 1.0 From: Mihir Luthra Date: Mon, 19 Aug 2019 22:39:53 +0530 Message-ID: Subject: undefined behaviour of return statement in /bin/sh and missing man entry To: freebsd-hackers@freebsd.org X-Rspamd-Queue-Id: 46C0mG1X5Kz43D2 X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=Fn48+bpl; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of luthramihir708@gmail.com designates 2607:f8b0:4864:20::944 as permitted sender) smtp.mailfrom=luthramihir708@gmail.com X-Spamd-Result: default: False [-3.99 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36]; FREEMAIL_FROM(0.00)[gmail.com]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; TO_DN_NONE(0.00)[]; IP_SCORE_FREEMAIL(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; IP_SCORE(0.00)[ip: (2.63), ipnet: 2607:f8b0::/32(-2.93), asn: 15169(-2.37), country: US(-0.05)]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; RCVD_IN_DNSWL_NONE(0.00)[4.4.9.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.b.8.f.7.0.6.2.list.dnswl.org : 127.0.5.0]; NEURAL_HAM_SHORT(-0.99)[-0.993,0]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+,1:+,2:~]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com.dwl.dnswl.org : 127.0.5.0] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Aug 2019 17:10:07 -0000 Hi everyone, Recently I was writing script on my virtual machine where I needed to know If a /bin/sh script has been sourced. I found many ways on stackoverflow, most of which only seem to work for bash. Although after some research, I found a way that should have worked with /bin/sh. It was that if I executed return from a function or sourced script, it should work fine and in other cases it should have wrote to stderr. Although on executing return on command line I got logged out and on executing same on non-login shells it just exited. Also, there seem to be no entry for return statement on man page of sh. [1] I have posted a brief explanation for the same in my stackoverfow question. [2]. [1] https://www.freebsd.org/cgi/man.cgi?query=sh&manpath=Unix+Seventh+Edition [2] https://stackoverflow.com/questions/57547626/detect-if-a-script-has-been-sourced-in-bin-sh Kind Regards, Mihir