Re: Use of pipe in $( filename | program) returns null
Am 28.11.2009 06:35, schrieb r...@saturn.syslang.net: Description: use of $( filename | program) does not work. It either should or it should be properly documented. The problem also happens on bash4. Repeat-By: qq=$( /etc/passwd | grep sys) echo $qq # result is null Fix: Either fix the docs to tell people that a pipe is not allowed or fix the code to allow it. The problem is not the pipe but the fact that 'filename' is an empty command which does nothing. If you want 'program' to read from 'file', use 'programfile'. Bernd -- Bernd Eggink http://sudrala.de
Re: Use of pipe in $( filename | program) returns null
Bernd Eggink mono...@sudrala.de writes: Am 28.11.2009 06:35, schrieb r...@saturn.syslang.net: Description: use of $( filename | program) does not work. It either should or it should be properly documented. The problem also happens on bash4. Repeat-By: qq=$( /etc/passwd | grep sys) echo $qq # result is null Fix: Either fix the docs to tell people that a pipe is not allowed or fix the code to allow it. The problem is not the pipe but the fact that 'filename' is an empty command which does nothing. If you want 'program' to read from 'file', use programfile'. Or even $( /etc/passwd grep sys). Andreas. -- Andreas Schwab, sch...@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 And now for something completely different.
Re: Use of pipe in $( filename | program) returns null
On Nov 28, 4:46 am, Andreas Schwab sch...@linux-m68k.org wrote: Bernd Eggink mono...@sudrala.de writes: Am 28.11.2009 06:35, schrieb r...@saturn.syslang.net: Description: use of $( filename | program) does not work. It either should or it should be properly documented. The problem also happens on bash4. Repeat-By: qq=$( /etc/passwd | grep sys) echo $qq # result is null Fix: Either fix the docs to tell people that a pipe is not allowed or fix the code to allow it. The problem is not the pipe but the fact that 'filename' is an empty command which does nothing. If you want 'program' to read from 'file', use programfile'. Or even $( /etc/passwd grep sys). Andreas. -- Andreas Schwab, sch...@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 And now for something completely different. Or even $(grep sys /etc/passwd)
Re: Use of pipe in $( filename | program) returns null
r...@saturn.syslang.net wrote: Description: use of $( filename | program) does not work. It either should or it should be properly documented. The problem also happens on bash4. Repeat-By: qq=$( /etc/passwd | grep sys) echo $qq # result is null Fix: Either fix the docs to tell people that a pipe is not allowed or fix the code to allow it. That construct is very limited. As the bash man page says: The command substitution $(cat file) can be replaced by the equivalent but faster $( file). That seems pretty clear. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/
Re: Use of pipe in $( filename | program) returns null
Chet Ramey wrote: r...@saturn.syslang.net wrote: Description: use of $( filename | program) does not work. It either should or it should be properly documented. The problem also happens on bash4. Repeat-By: qq=$( /etc/passwd | grep sys) echo $qq # result is null Fix: Either fix the docs to tell people that a pipe is not allowed or fix the code to allow it. That construct is very limited. As the bash man page says: The command substitution $(cat file) can be replaced by the equivalent but faster $( file). That seems pretty clear. Yeah, and then based on that he probably thought that $(cat file | grep sys) could be replaced by $( file | grep sys) which is not the case.
Use of pipe in $( filename | program) returns null
Configuration Information [Automatically generated, do not change]: Machine: i386 OS: linux-gnu Compiler: gcc Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='i386' -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i386-redhat-linux-gnu' -DCONF_VENDOR='redhat' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -I. -I. -I./include -I./lib -D_GNU_SOURCE -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i386 -mtune=generic -fasynchronous-unwind-tables uname output: Linux saturn.syslang.net 2.6.27.30-170.2.82.fc10.i686.PAE #1 SMP Mon Aug 17 08:24:23 EDT 2009 i686 athlon i386 GNU/Linux Machine Type: i386-redhat-linux-gnu Bash Version: 3.2 Patch Level: 39 Release Status: release Description: use of $( filename | program) does not work. It either should or it should be properly documented. The problem also happens on bash4. Repeat-By: qq=$( /etc/passwd | grep sys) echo $qq # result is null Fix: Either fix the docs to tell people that a pipe is not allowed or fix the code to allow it.
