Path: csiph.com!goblin1!goblin.stu.neva.ru!usenet.stanford.edu!not-for-mail From: Peng Yu Newsgroups: gnu.bash.bug Subject: Should [[ -v 1 ]] be supported? Date: Wed, 26 Dec 2018 21:49:38 -0600 Lines: 108 Approved: bug-bash@gnu.org Message-ID: NNTP-Posting-Host: lists.gnu.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: usenet.stanford.edu 1545882602 3597 208.118.235.17 (27 Dec 2018 03:50:02 GMT) X-Complaints-To: action@cs.stanford.edu To: bug-bash Envelope-to: bug-bash@gnu.org 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=Ep+fOd1KTO2HtQx9wbAFEyZ+ocqzGid7YqQ8z6XfF68=; b=An9AifNU5NUBxPQ/Kf1ORDX9FPNowBVllLOOYZsxQYYsMRteCPDdzE/14wjxlJJemA RnGPD/PJtjQAAX2Rpq+nuESj4ljDmPAs73vLk06JM6Be2AYu9E20qpVjRKM+5BRQNopJ uLsK/7/kBWTDHrHhvNXPrNoyqJ0wUuEqvkHM7M/xFycVxdicS9JjwmfYhWryt5UWxwUj +f7z7tyUNRloZg6+tKpR07s4DrjZij/y0Wsu+S1I+vBsa2pYCguUwjEwpA2bLTccSBvA XY/M3WH97fhlKYYwpVoHKBxXnBZ/4KTtdeWm6ED7D0Vr+yss8FcnD9e46ReWud+VsppK vrww== 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=Ep+fOd1KTO2HtQx9wbAFEyZ+ocqzGid7YqQ8z6XfF68=; b=iuiugcCKpXupsLa3G1qyRR6qR90m6+70RZ/Ik77emyxavTxFZrrnjmbdNQa43cxXjy nC1mmuFE1JrFwkSxdPLTgFFGWfIyuvH6zTRVl6okiEOynaDen489bgeNoh9YT490kHUW 7Lrr1xa2mRtOp5uvERqZCZ2yMIZUIE1wWFyFG+KLYmjRT+GNdAqtzG9IBs1YcIrAClAn Gr93LDIwey2Hl1ajOa+29Nq1YIlcWn6jg1f+PE4/NQBpRVFeMRWFwx+clUPEYn2RzlNy syWqupxN9lrI3ziCJCHdQSbFSCLFusJ6j+Y4Zei+x2mxkpM2SNuI2MKr/n2GzzF6mEiL /N3A== X-Gm-Message-State: AJcUukf4ObyzVR31Wps0+iLEZzo66TXu/2PXChoC62SJM09Z+EU7l3qp PeDJ3tDMjn6m7UBDAc+H7uTt7wASveA1zGFRtfnklCsz X-Google-Smtp-Source: ALg8bN7R7bYdBQSwVSY4PrmkLfxofg4s22+Zznmj/afNg/qhDZj/FCaH7MoryENJlndkDNt6LCa7XBPBlhIelSXAAfA= X-Received: by 2002:a6b:6b02:: with SMTP id g2mr11032721ioc.18.1545882592194; Wed, 26 Dec 2018 19:49:52 -0800 (PST) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::d32 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:14966 Hi, [[ -v 1 ]] does not work for $1. $ [ -v 1 ]; echo "$?" 1 $ set -- a $ [ -v 1 ]; echo "$?" 1 Although [[ -z ${1+s} ]] and (($#)) works for testing if $1 is set, neither of them are uniformly better performance wise. In this case, should [[ -v 1 ]] be supported? set -- $(seq 1) time for ((i=0;i<10000;++i)); do (($#)) done real 0m0.140s user 0m0.132s sys 0m0.001s time for ((i=0;i<10000;++i)); do [[ -z ${1+s} ]] done real 0m0.216s user 0m0.151s sys 0m0.000s time for ((i=0;i<10000;++i)); do [[ -z ${1+s} ]] done real 0m0.336s user 0m0.156s sys 0m0.009s set -- $(seq 10) time for ((i=0;i<10000;++i)); do (($#)) done real 0m0.224s user 0m0.130s sys 0m0.001s time for ((i=0;i<10000;++i)); do [[ -z ${1+s} ]] done real 0m0.256s user 0m0.147s sys 0m0.000s set -- $(seq 100) time for ((i=0;i<10000;++i)); do (($#)) done real 0m0.260s user 0m0.131s sys 0m0.001s time for ((i=0;i<10000;++i)); do [[ -z ${1+s} ]] done real 0m0.244s user 0m0.146s sys 0m0.001s set -- $(seq 1000) time for ((i=0;i<10000;++i)); do (($#)) done real 0m0.338s user 0m0.167s sys 0m0.002s time for ((i=0;i<10000;++i)); do [[ -z ${1+s} ]] done real 0m0.277s user 0m0.144s sys 0m0.000s set -- $(seq 10000) time for ((i=0;i<10000;++i)); do (($#)) done real 0m1.012s user 0m0.540s sys 0m0.011s time for ((i=0;i<10000;++i)); do [[ -z ${1+s} ]] done real 0m0.292s user 0m0.148s sys 0m0.003s -- Regards, Peng