`if $(cmd);' is a positive when there's no output from cmd
Hey all, $ if $(echo string >/dev/null); then echo true; fi true This should be a syntax error, since $ if; then echo true; fi bash: syntax error near unexpected token `;' Tested on GNU bash, version 2.05b.0(1)-release (i386-pc-linux-gnu) Copyright (C) 2002 Free Software Foundation, Inc. and GNU bash, version 3.1.7(1)-release (i386-redhat-linux-gnu) Copyright (C) 2005 Free Software Foundation, Inc. Regards ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
Re: `if $(cmd);' is a positive when there's no output from cmd
Em (02:25:11), Andreas Schwab escreveu: > >> Hey all, >> >> $ if $(echo string >/dev/null); then echo true; fi >> true >> >> This should be a syntax error > >No, it is a perfectly valid command, syntactically. That the command >substitution expands to nothing has no significance any more once the >command is parsed, just like shell meta characters resulting from >expansions are taken literally. > >Andreas. That's not true.. try: $ echo $(echo \*) or $ a=*; echo "$a"; echo $a for illustration. Regards ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
Re: `if $(cmd);' is a positive when there's no output from cmd
Em (21:43:32), Mike Frysinger escreveu: >On Saturday 15 April 2006 19:55, Herculano Einloft wrote: >> $ if $(echo string >/dev/null); then echo true; fi >> true >> >> This should be a syntax error, since >> >> $ if; then echo true; fi >> bash: syntax error near unexpected token `;' > >the first command statement is more like: >if :; then echo true; fi >-mike Hey mike.. Care to explain that? I still see a difference between $ if $(echo :); then echo true; fi which would be your example, and $ if $(:); then echo true; fi which would be mine Regards ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
Re: `if $(cmd);' is a positive when there's no output from cmd
Em (02:25:11), Andreas Schwab escreveu: >Herculano Einloft writes: > >> Hey all, >> >> $ if $(echo string >/dev/null); then echo true; fi >> true >> >> This should be a syntax error > >No, it is a perfectly valid command, syntactically. That the command >substitution expands to nothing has no significance any more once the >command is parsed, just like shell meta characters resulting from >expansions are taken literally. > >Andreas. > Anyway, I see your point. It can't be a syntax error, since of course it parses correctly. It's kind of a weird case though, but I guess that's it. Thanks all ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
