Very Computer

in comp.unix.misc i read:

Quote:>I'm sorry but it's the ONLY way I can write this.  I don't know how to
>read standard in in TCL; I don't know how to do complex string
>manipulation in Bash.  So I have to write in the languages based on
>what I know.

in terms of shell scripting you don't have much debugging experience, in
particular you don't appear to have used ``set -vx'' to expose the
operations occurring.  which would lead to the real problem: you aren't
using enough quoting, which is causing ...

Quote:>Problem arises in fileremoval.sh - it just plain does not work, here
>is the error:

>/home/phillip/scripts/fileremoval.sh: [: ==: unary operator expected

my little test script, which is whittled down to just the problem, is:

  #!/usr/bin/bash
  set -x
  foo=''
  [ $foo == 'Y' ]

executing this provides the following output:

  + foo=
  + '[' == Y ']'
  ./foo.sh: line 4: [: ==: unary operator expected

as you can see there is no argument before the == (which is non-standard
btw), because foo is empty.  to ensure that an argument is created you need
to use quotes, i.e.,

  #!/usr/bin/bash
  set -x
  foo=''
  [ "$foo" == 'Y' ]

which after expansion becomes:

  + foo=
  + '[' '' == Y ']'

there we see that there is an empty argument being provided.

--
a signature

Quote:> [fu-t set]

> in comp.unix.misc i read:

> >I'm sorry but it's the ONLY way I can write this.  I don't know how to
> >read standard in in TCL; I don't know how to do complex string
> >manipulation in Bash.  So I have to write in the languages based on
> >what I know.

> perhaps you should resolve these deficiencies -- not that there is anything
> wrong with using tcl from bash or bash from tcl, but it doesn't appear
> necessary in this case.

> in terms of shell scripting you don't have much debugging experience, in
> particular you don't appear to have used ``set -vx'' to expose the
> operations occurring.  which would lead to the real problem: you aren't
> using enough quoting, which is causing ...

Quote:

> >Problem arises in fileremoval.sh - it just plain does not work, here
> >is the error:

> >/home/phillip/scripts/fileremoval.sh: [: ==: unary operator expected

> you have a test which expects certain arguments and they are not being
> provided.  you use bare variable expansion, which does not result in an
> argument being created if the variable is unset or empty.  let's look at
> what that looks like using set -x.

> my little test script, which is whittled down to just the problem, is:

>   #!/usr/bin/bash
>   set -x
>   foo=''
>   [ $foo == 'Y' ]

> executing this provides the following output:

>   + foo=
>   + '[' == Y ']'
>   ./foo.sh: line 4: [: ==: unary operator expected

> as you can see there is no argument before the == (which is non-standard
> btw), because foo is empty.  to ensure that an argument is created you need
> to use quotes, i.e.,

>   #!/usr/bin/bash
>   set -x
>   foo=''
>   [ "$foo" == 'Y' ]

> which after expansion becomes:

>   + foo=
>   + '[' '' == Y ']'

> there we see that there is an empty argument being provided.

if [ $foo ] && [ $foo == 'Y' ]; then; #blah; fi

But that is my C-derivative background coming into play.  In most
C-derivative languages nullness is handled a lot more friendly than
shell or bash script.  Ok , is it "shell script" or "bash script"?
Which is the correct term to use?

Thanx again
Phil

in comp.unix.shell i read:

Quote:>BTW I use "==" because it works, whether it's non-standard or not
>is irrelevant when I get all kinds of errors with -eq for strings.  

Quote:>Ok , is it "shell script" or "bash script"?
>Which is the correct term to use?

--
a signature

:  Ok , is it "shell script" or "bash script"?
:Which is the correct term to use?

If the script uses bash specific features, it probably is more correct
to say "bash script".  Otherwise, most just say "shell script".

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Even if explicitly stated to the contrary, nothing in this posting
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