History expansion is performed before variable expansion. >From man bash:
History expansion is performed immediately after a complete line is read, before the shell breaks it into words. and ! Start a history substitution, except when ***followed by a blank***, newline, carriage return, = or ( (when the extglob shell option is enabled using the shopt builtin). [emphasis mine] On Tue, Jul 27, 2010 at 1:01 PM, <jer...@nickurak.ca> 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 -g -O2 > -Wall > uname output: Linux figment 2.6.32-24-server #38-Ubuntu SMP Mon Jul 5 > 10:29:32 UTC 2010 x86_64 GNU/Linux > Machine Type: x86_64-pc-linux-gnu > > Bash Version: 4.1 > Patch Level: 5 > Release Status: release > > Description: > > Event-catching seems to be catching cases it shouldn't. In particular, $! is > caught as an event. > > Repeat-By: > > This command fails as follows: > >> nicku...@woking:~$ sleep 5 & PID=$!; echo "pid is $PID" >> bash: !: event not found > > Adding quotation marks doesn't help: > >> nicku...@woking:~$ sleep 5 & PID="$!"; echo "pid is $PID" >> bash: !": event not found > > As a workaround, adding whitespace after the ! fixes it: > >> nicku...@woking:~$ sleep 5 & PID=$! ; echo "pid is $PID" >> [1] 1614 >> pid is 1614 > > or > >> nicku...@woking:~$ sleep 5 & PID="$! "; echo "pid is $PID" >> [3] 2048 >> pid is 2048 > >
