Re: Big bug in shell scripting in Applescript
Re: Big bug in shell scripting in Applescript
- Subject: Re: Big bug in shell scripting in Applescript
- From: Axel Luttgens <email@hidden>
- Date: Fri, 05 Aug 2011 10:50:25 +0200
Le 5 août 2011 à 00:08, Zavatone, Alex a écrit :
> Think I found a big bug in sed or shell scripting in AppleScript.
>
> Copy the code below, run and look at the output.
>
> \n gets appended to the last line of the return string every time this is run.
>
> […]
Hello Alex,
As always, trying to convey a problem thru a very simplified example is the best way to go:
do shell script "sed 's:^a::'<<<'abcdefg'" without altering line endings
--> "bcdefg
"
So, yes, a linefeed appears to be appended.
Let's thus try in terminal:
luttgens$ sed 's:^a::'<<<'abcdefg'
bcdefg
luttgens$
A linefeed as well thus.
Looking at sed's man page:
Normally, sed cyclically copies a line of input, not including its termi-
nating newline character, into a pattern space, (unless there is some-
thing left after a ``D'' function), applies all of the commands with
addresses that select that pattern space, copies the pattern space to the
standard output, appending a newline, and deletes the pattern space.
Clearly, sed is devised to handle a stream of input lines and to produce a stream of output lines accordingly to standard unix conventions.
No bug in sed, nor in shell scripting.
Now, about AppleScript's "do shell script" and its "altering line endings":
Should the do shell script command change all line endings in the
command output to Mac-style and trim a trailing one? For example,
the result of do shell script "echo foo; echo bar" is "foo\rbar",
not the "foo\nbar\n" that the shell script actually returned.
Default Value:
true
Again, your results agree with a documented behavior.
As a result, it would tend to believe there is no big bug at all… ;-)
HTH,
Axel
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