On Tue, Dec 24, 2013 at 12:57 AM, rens <rens.groenewe...@xs4all.nl> wrote:
> > Subject: [50 character or so descriptive subject here (for reference)] > > Configuration Information [Automatically generated, do not change]: > Machine: x86_64 > OS: linux-gnu > Compiler: gcc -I/home/abuild/rpmbuild/BUILD/bash-4.2 > -L/home/abuild/rpmbuild/BUILD/bash-4.2/../readline-6.2 > Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' > -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-suse-linux-gnu' > -DCONF_VENDOR='suse' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' > -DSHELL -DHAVE_CONFIG_H -I. -I. -I./include -I./lib -fmessage-length=0 > -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables > -fasynchronous-unwind-tables -g -D_GNU_SOURCE -DRECYCLES_PIDS -Wall -g > -std=gnu89 -Wuninitialized -Wextra -Wno-unprototyped-calls -Wno-switch-enum > -Wno-unused-variable -Wno-unused-parameter -ftree-loop-linear -pipe > -fprofile-use > uname output: Linux dep2.fritz.box 3.7.10-1.16-default #1 SMP Fri May 31 > 20:21:23 UTC 2013 (97c14ba) x86_64 x86_64 x86_64 GNU/Linux > Machine Type: x86_64-suse-linux-gnu > > Bash Version: 4.2 > Patch Level: 42 > Release Status: release > bug-bash@gnu.org > Description: > [Detailed description of the problem, suggestion, or complaint.] > > Hello, > > this script: > _______________________ > export cval=0 > echo entering while > > # listing ten files, to generate some output to count. > ls -1 /usr/bin|head -10 |while read fname > do > cval=$(( cval +1 )) > echo cval = $cval file = $fname > done > # one would think cval is now 10. but it is not, contrary to any other > programming language........ > > echo " after while: cval = $cval" > _______________________________ > > does not set the value of cval after exiting the while loop. > > that makes no sense. > > Please Don't bother to tell me it s the way you guys think it should > technically work. > I know you think something along those lines, at least thats what I am > told.... > > However, no one in this world having to solve real life issues with > software, is interested in how it technically works. we need real life > logic and software that can deal with real life challenges and requirements. > > Bash should not work that way. no programming language handles logic this > way. Not pascal, korn shell, c shell, cobol, c, c++, lua , fortran or any > other language i ever used. > Actually only ksh93 doesn't work this way, other "ksh" variants work like bash. In newer bash you can do, if job control is disable (that is in a script): shopt -s lastpipe. Note that even with this, only the right hand side doesn't run in a forked subshell, eg in ksh93 or bash with last pipe: var=foo | true;echo $var # prints nothing At least one side of the pipe has to be in a child process. The same thing is true if you use a pipe and fork a process in these other languages you mention.
