Shell programming 101: Is this an expr(1) bug ?
Running: #!/bin/sh set -ex for p in ad2 ad0 ad1 do a0=`expr $p : '^ad\([0-9]\)$'` done I get: syv# sh _ + expr ad2 : ^ad\([0-9]\)$ + a0=2 + expr ad0 : ^ad\([0-9]\)$ + a0=0 syv# echo $? 1 syv# That looks like a bug to me... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Shell programming 101: Is this an expr(1) bug ?
On Tue, 2003-02-18 at 06:39, Poul-Henning Kamp wrote: + expr ad0 : ^ad\([0-9]\)$ + a0=0 syv# echo $? 1 syv# That looks like a bug to me... hilfy:202 Z$ /bin/expr ad0 : '^ad\([0-9]\)$' 0 zsh: exit 1 /bin/expr ad0 : '^ad\([0-9]\)$' (Solaris 8 box) The Solaris manpage claims: EXIT STATUS As a side effect of expression evaluation, expr returns the following exit values: (...) 1 if the expression is either NULL or 0 So it looks like correct behavior, if slightly odd in this particular context. -- brandon s allbery [openafs/solaris/japh/freebsd] [EMAIL PROTECTED] system administrator [linux/heimdal/too many hats] [EMAIL PROTECTED] electrical and computer engineering KF8NH carnegie mellon university [better check the oblivious first -ke6sls] To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Shell programming 101: Is this an expr(1) bug ?
On Tue, Feb 18, 2003 at 12:39:22PM +0100, Poul-Henning Kamp wrote: Running: #!/bin/sh set -ex for p in ad2 ad0 ad1 do a0=`expr $p : '^ad\([0-9]\)$'` done I get: syv# sh _ + expr ad2 : ^ad\([0-9]\)$ + a0=2 + expr ad0 : ^ad\([0-9]\)$ + a0=0 syv# echo $? 1 syv# That looks like a bug to me... Confusing but documented behaviour: 1. expr ad0 : ad\([0-9]\) = expr 0 man expr If the match succeeds and the pattern contains at least one regu- lar expression subexpression ``\(...\)'', the string correspond- ing to ``\1'' is returned; otherwise the matching operator 2. `expr 0` = exit status = 1 man expr The expr utility exits with one of the following values: 0 the expression is neither an empty string nor 0. 1 the expression is an empty string or 0. This behaviour is the same on linux, *BSD and probably other systems too. Regards Adi To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Shell programming 101: Is this an expr(1) bug ?
Running: #!/bin/sh set -ex for p in ad2 ad0 ad1 do a0=`expr $p : '^ad\([0-9]\)$'` done I get: syv# sh _ + expr ad2 : ^ad\([0-9]\)$ + a0=2 + expr ad0 : ^ad\([0-9]\)$ + a0=0 syv# echo $? 1 The `set -e' says to exit the shell if a simple command fails. POSIX.2 says that the exit status of an assignment statement without an accompanying command is either 0 or the exit status of the last command substitution performed while expanding the rhs. `expr' returns 1 when the result is `0'. Thus the assignment statement fails and the shell exits. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ( ``Discere est Dolere'' -- chet ) Chet Ramey, ITS, CWRU[EMAIL PROTECTED]http://cnswww.cns.cwru.edu/~chet/ To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
