On 10 Apr 2012, at 06:03, Elliott Forney wrote:
> Here is another example that appears to defy my expectations. In this
> case, the semicolon is allowed:
>
> sine:~$ hello='echo hello'
> sine:~$ world='echo world'
> sine:~$ ${hello};${world}
> hello
> world
> sine:~$ unset hello
> sine:~$ ${hello};${world}
> world
> sine:~$ unset world
> sine:~$ ${hello};${world}Those are not empty statements. It's important to understand the difference between: $var and: eval "$var" People should stop trying to execute code by parameter expansion, and specifically stop thinking that parameter-expanded words are evaluated as bash code. > > Thanks! > Elliott Forney > > On Mon, Apr 9, 2012 at 10:02 PM, Elliott Forney > <elliott.for...@gmail.com> wrote: >> Sure, a comment can be used to place a line in your history but that >> doesn't really address the examples I had. Just seems to me like a >> lone semicolon could be treated as a newline/noop. I can't seem to >> think of anything that this would break but, of course, that doesn't >> mean it wouldn't. The end of a case in a switch statement is >> certainly an interesting one, hadn't thought of that, but it should be >> possible to handle that by checking for ;; as a token before ;. OK, so you're saying, let's change bash so that an empty statement becomes a noop statement. Except for when that empty statement is preceded by a semicolon and happens to have no whitespace, because then it could be a case delimiter. Frankly, what are you hoping to gain from this? This will just introduce new rules with new exceptions and inconsistencies. If it were possible to do a blanket rule: empty statements before a semicolon are noops, I might be OK with it, but if it requires adding additional addendums to the rule, "oh wait, except for this and that case", my vote is out. >> >> I might mention that ksh, zsh and tcsh all allow lines to begin with a >> semicolon. zsh even allows "; ; ; echo hello world ; ; ;" although >> ksh only allows a single ; at the beginning of a line. >> >> On Sun, Apr 8, 2012 at 6:48 PM, Joseph Fredette <jfred...@gmail.com> wrote: >>> Could also use a #, no? >>> >>> On Sun, Apr 8, 2012 at 8:46 PM, Steven W. Orr <ste...@syslang.net> wrote: >>> >>>> On 4/7/2012 4:00 PM, Elliott Forney wrote: >>>> >>>>> I wish bash would happily execute lines that begin with a semicolon, >>>>> i.e., treat it as a no-op followed by a command. The following >>>>> examples come to mind: >>>>> >>>>> $ infloop& echo hello >>>>> [2] 11361 >>>>> hello >>>>> $ infloop&; echo hello >>>>> bash: syntax error near unexpected token `;' >>>>> >>>>> $ echo hello; echo world >>>>> hello >>>>> world >>>>> $ echo hello;; echo world >>>>> bash: syntax error near unexpected token `;;' >>>>> >>>>> $ ; echo hello world >>>>> bash: syntax error near unexpected token `;' >>>>> >>>>> Any thoughts? >>>>> >>>>> Thanks, >>>>> Elliott Forney >>>>> >>>> >>>> Just use a colon. >>>> >>>> : echo Hello world. >>>> >>>> I use it all the time to 'park' a command in my history. Then when I'm >>>> ready, I just back up to it and remove the colon. >>>> >>>> >>>> -- >>>> Time flies like the wind. Fruit flies like a banana. Stranger things have >>>> .0. >>>> happened but none stranger than this. Does your driver's license say Organ >>>> ..0 >>>> Donor?Black holes are where God divided by zero. Listen to me! We are all- >>>> 000 >>>> individuals! What if this weren't a hypothetical question? >>>> steveo at syslang.net >>>> >>>> >
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