Incorrect exit status of the Build-IN (( ))
Configuration Information [Automatically generated, do not change]: Machine: x86_64 OS: linux-gnu Compiler: gcc Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' -DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL -DH AVE_CONFIG_H -I. -I../bash -I../bash/include -I../bash/lib -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Wformat-security -Werror=format-security -Wall uname output: Linux ESO0560-ubuntu 3.2.0-25-generic #40-Ubuntu SMP Wed May 23 20:30:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux Machine Type: x86_64-pc-linux-gnu Bash Version: 4.2 Patch Level: 24 Release Status: release Description: PROBLEM: Exit status not correct, when count up from zero using Build-in (( )) EXAMPLE (enter each following line in Bash): a=0 ((a++)) echo $? echo $a ((a++)) echo $? echo $a COMMENTS TO EXMAPLE: The first ((a++)) should perform 'a+1' --> '0+1' (correct operation) The first 'echo $?' returns '1' which is not correct, since following 'echo $a' returns '1' (result of adding 0+1) which is correct
Re: Incorrect exit status of the Build-IN (( ))
On Fri, Dec 7, 2012 at 12:52 PM, Orlob Martin (EXT) < extern.martin.or...@esolutions.de> wrote: > Configuration Information [Automatically generated, do not change]: > Machine: x86_64 > OS: linux-gnu > Compiler: gcc > Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' > -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' > -DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL > -DHAVE_CONFIG_H -I. -I../bash -I../bash/include -I../bash/lib > -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector --param=ssp-buffer-size=4 > -Wformat -Wformat-security -Werror=format-security -Wall > uname output: Linux ESO0560-ubuntu 3.2.0-25-generic #40-Ubuntu SMP Wed May > 23 20:30:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux > Machine Type: x86_64-pc-linux-gnu > > Bash Version: 4.2 > Patch Level: 24 > Release Status: release > > Description: > PROBLEM: Exit status not correct, when count up from zero using > Build-in (( )) > > EXAMPLE (enter each following line in Bash): > a=0 > ((a++)) > echo $? > echo $a > ((a++)) > echo $? > echo $a > COMMENTS TO EXMAPLE: > The first ((a++)) should perform 'a+1' --> '0+1' (correct > operation) > The first 'echo $?' returns '1' which is not correct, since > following 'echo $a' returns '1' (result of adding 0+1) which is > correct > Not a bug, a++ adds one to "a" but the result of the expression is the value of a before the increment, so it's 0. you can see it using echo $((a++)) instead of ((a++)) ((++a)) does what you expect.
Re: Incorrect exit status of the Build-IN (( ))
This is the expected behavior, and it's the same in any language with a '++' syntax. var++ is POST-incrementing, that means the '+1' happens AFTER the expansion. If you want it to happen before, you need pre-incrementing. ++var. On Fri, Dec 7, 2012 at 5:52 AM, Orlob Martin (EXT) < extern.martin.or...@esolutions.de> wrote: > Configuration Information [Automatically generated, do not change]: > Machine: x86_64 > OS: linux-gnu > Compiler: gcc > Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' > -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' > -DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL > -DHAVE_CONFIG_H -I. -I../bash -I../bash/include -I../bash/lib > -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector --param=ssp-buffer-size=4 > -Wformat -Wformat-security -Werror=format-security -Wall > uname output: Linux ESO0560-ubuntu 3.2.0-25-generic #40-Ubuntu SMP Wed May > 23 20:30:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux > Machine Type: x86_64-pc-linux-gnu > > Bash Version: 4.2 > Patch Level: 24 > Release Status: release > > Description: > PROBLEM: Exit status not correct, when count up from zero using > Build-in (( )) > > EXAMPLE (enter each following line in Bash): > a=0 > ((a++)) > echo $? > echo $a > ((a++)) > echo $? > echo $a > COMMENTS TO EXMAPLE: > The first ((a++)) should perform 'a+1' --> '0+1' (correct > operation) > The first 'echo $?' returns '1' which is not correct, since > following 'echo $a' returns '1' (result of adding 0+1) which is > correct > > > >
