From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11819 invoked from network); 21 May 1999 10:19:08 -0000 Received: from sunsite.auc.dk (130.225.51.30) by ns1.primenet.com.au with SMTP; 21 May 1999 10:19:08 -0000 Received: (qmail 15927 invoked by alias); 21 May 1999 10:18:49 -0000 Mailing-List: contact zsh-workers-help@sunsite.auc.dk; run by ezmlm Precedence: bulk X-No-Archive: yes X-Seq: 6324 Received: (qmail 15920 invoked from network); 21 May 1999 10:18:47 -0000 From: "Bart Schaefer" Message-Id: <990521101836.ZM9723@candle.brasslantern.com> Date: Fri, 21 May 1999 10:18:36 +0000 In-Reply-To: <001a01bea361$994a2140$21c9ca95@mow.siemens.ru> Comments: In reply to "Andrej Borsenkow" "Speed of ZSH" (May 21, 12:11pm) References: <001a01bea361$994a2140$21c9ca95@mow.siemens.ru> X-Mailer: Z-Mail (5.0.0 30July97) To: "Andrej Borsenkow" , "ZSH workers mailing list" Subject: Re: Speed of ZSH MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii On May 21, 12:11pm, Andrej Borsenkow wrote: } Subject: Speed of ZSH } } I recently needed to do a quick prototyping, and selected zsh just for the } easy programming. The task was: I get a file with records of length 2040 } characters and need to extract several (~100) fixed width fields and write } them out separated by tabs. I had a list of fields in the form n1-n2, so I } just vi'ed them :-) to get $line[n1,n2]. } } The problems I got were: } } 1. I found, that it is near to impossible to ``read'' line without breaking } it on IFS. ``read -k'' did not work :-( You have to combine it with -u to get the desired effect, and you need to use -r to prevent backslash-interpretation. I tried to explain about this in my rewrite of the "read" info in 3.1.5, but maybe I didn't do a good enough job. (It's also a bit odd that a space must precede the argument to -k and must not precede the argument to -u, at least as the 3.0.5 code stands.) read -ru0 -k 2040 block < file } 2. It is impossible to ``print'' arguments separated by user defined string } (only NL or NUL). Unless there are embedded NULs in the input, just use "tr": print -rN -- "$block[n1,n2]" "$block[n3,n4]" ... | tr '\0' '\11' But: } I had to make an array out of fields, and then print it } with explicit join: } } fields=( $line[n1,n2] ...) } print ${(j/\t/)fields} If you're already spelling it all out like that, why not use a single quoted string and put in the tabs yourself? print -r -- "$block[n1,n2] $block[n3,n4] ..." It won't be pretty, but it'll get the job done. } After doing it I found, that ZSH needs several seconds for a file with 28 } records! That is really too much for such a simple task. I suspect, the } reason is constant reallocation of memory when first array is created } (remember, it has about 100 elements) and then when it is joined. You're probably right. There are good and bad ways to write programs in any language. Simply doing the read/print isn't that slow (though about 8 times slower than dd, look at the user seconds): zagzig[31] time while read -ru0 -k 2040 block ; do print -r -- "$block"; done < /etc/termcap | dd bs=2040 of=/dev/null 213+198 records in 213+198 records out while read -ru0 -k 2040 block; do; print -r -- "$block"; done < /etc/termcap 0.79s user 0.07s system 93% cpu 0.917 total dd bs=2040 of=/dev/null 0.01s user 0.02s system 3% cpu 0.875 total -- Bart Schaefer Brass Lantern Enterprises http://www.well.com/user/barts http://www.brasslantern.com