Bash interprets $! as an event
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
Re: Bash interprets $! as an event
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
Indirect expansion and arrays
It seems that indirect expansion doesn't work with arrays:
$ a=(x y z)
$ b=a
$ echo ${!b[0]} ${!b[1]} ${!b[2]}
x
Is that intended? The documentation isn't explicit about it.
IMHO it would be very desirable to have a indirect expansion facility
for arrays. Otherwise there is only a choice between passing all
elements to a function, which is time-consuming, or using eval, which is
cumbersome and error-prone.
Regards,
Bernd
--
Bernd Eggink
http://sudrala.de
Re: Indirect expansion and arrays
To make your example work try:
$ b=a[*]
or
$ b...@]
Otherwise, your indirection is telling b to look at a as a scalar.
This would give the same result:
$ echo $a
x
On Thu, Jul 29, 2010 at 3:55 PM, Bernd Eggink mono...@sudrala.de wrote:
It seems that indirect expansion doesn't work with arrays:
$ a=(x y z)
$ b=a
$ echo ${!b[0]} ${!b[1]} ${!b[2]}
x
Is that intended? The documentation isn't explicit about it.
IMHO it would be very desirable to have a indirect expansion facility for
arrays. Otherwise there is only a choice between passing all elements to a
function, which is time-consuming, or using eval, which is cumbersome and
error-prone.
Regards,
Bernd
--
Bernd Eggink
http://sudrala.de
Re: Indirect expansion and arrays
Oops, sorry, that converts all of a to a scalar b so ${b[0]} gives x
y z and ${b[1]} gives nothing.
On Thu, Jul 29, 2010 at 7:16 PM, Dennis Williamson
dennistwilliam...@gmail.com wrote:
To make your example work try:
$ b=a[*]
or
$ b...@]
Otherwise, your indirection is telling b to look at a as a scalar.
This would give the same result:
$ echo $a
x
On Thu, Jul 29, 2010 at 3:55 PM, Bernd Eggink mono...@sudrala.de wrote:
It seems that indirect expansion doesn't work with arrays:
$ a=(x y z)
$ b=a
$ echo ${!b[0]} ${!b[1]} ${!b[2]}
x
Is that intended? The documentation isn't explicit about it.
IMHO it would be very desirable to have a indirect expansion facility for
arrays. Otherwise there is only a choice between passing all elements to a
function, which is time-consuming, or using eval, which is cumbersome and
error-prone.
Regards,
Bernd
--
Bernd Eggink
http://sudrala.de
