Dang it! I may coincidentally have just found a fairly profound
bash bug related to usage of that spew | while read idiom.
Here's what I do to cause bash to say Segmentation fault
cd /
find . -type f | while read f
do
ls -laFd $f
done
Collecting the list in a file first
Interesting:
find . -type f | while read f; do true $f ; done #Builtin - works
find . -type f | while read f; do /bin/true $f ; done #Chokes
...a memory leak somewhere in the fork() path?
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On Wed, 24 Apr 2002, at 10:43am, Michael O'Donnell wrote:
...a memory leak somewhere in the fork() path?
Try:
while true ; do /bin/true ; done
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Ben Scott [EMAIL PROTECTED]
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In a message dated: Wed, 24 Apr 2002 10:53:58 EDT
Benjamin Scott said:
Try:
while true ; do /bin/true ; done
I think there's a bug here. Nothing happens, well, at least not so far... ;)
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On Wed, 24 Apr 2002, at 10:57am, [EMAIL PROTECTED] wrote:
Nothing happens ...
Try xyzzy. ;-)
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Ben Scott [EMAIL PROTECTED]
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pll wrote:
while true ; do /bin/true ; done
I think there's a bug here. Nothing happens, well, at least not so far... ;)
Well, we ARE getting pretty minimalistic here.
Of course, if it's true that
Every program has at least one bug.
...and
Every program can be reduced in
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In a message dated: Wed, 24 Apr 2002 11:02:46 EDT
Michael O'Donnell said:
...then
Every program can be reduced to one
instruction that does not work.
I thought it was:
Every program can
Ha! I haven't analyzed this yet (and might never) but running bash
under GDB (actually, I attached GDB to the child bash proc) yields:
Program received signal SIGABRT, Aborted.
0x400497b1 in kill () from /lib/libc.so.6
(gdb) where
#0 0x400497b1 in kill () from /lib/libc.so.6
#1
This is a VAX system you're trying it on?!? :)
On Wed, 24 Apr 2002, Benjamin Scott wrote:
Try xyzzy. ;-)
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In a message dated: Wed, 24 Apr 2002 11:32:38 EDT
Michael O'Donnell said:
Ha! I haven't analyzed this yet (and might never) but running bash
under GDB (actually, I attached GDB to the child bash proc)
I'm interpreting this as an out-of-memory error as
a result of too many file names filling up an array?
Is that an accurate interpretation of this trace?
Nope - this problem was detected (though not necessarily
caused) in the implementation of malloc()/free() that comes
with the bash
On Wed, 24 Apr 2002, at 11:47am, [EMAIL PROTECTED] wrote:
I'm interpreting this as an out-of-memory error as a result of too many
file names filling up an array? Is that an accurate interpretation of
this trace?
No, what happened is that the heap management routines detected a
corrupion
On Wed, Apr 24, 2002 at 11:47:28AM -0400, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
If so, why would you use an array for this sort of thing. Way back
in time when I was taking Intro to Programming, they taught us to use
linked lists for this type of scenario where you didn't know up front
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In a message dated: Mon, 22 Apr 2002 17:48:27 EDT
Benjamin Scott said:
On Mon, 22 Apr 2002, at 2:15pm, [EMAIL PROTECTED] wrote:
If they only exist within bash, then I wouldn't advocate their use if
Derek D. Martin [EMAIL PROTECTED] writes:
At some point hitherto, Kevin D. Clark hath spake thusly:
In general, the inner part of the loop is run in a sub-shell.
Not exactly... it's more subtle even than that. For example:
Yes, my language could have been a little tighter there. In
This is a classic example of why I prefer doing actual
script work in ksh and have my login shell as bash.
Aren't you just saying that you prefer to stick with a
familiar set of idiosyncracies for scripting purposes?
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To
On Tue, 23 Apr 2002, at 11:00am, Michael O'Donnell wrote:
This is a classic example of why I prefer doing actual
script work in ksh and have my login shell as bash.
Aren't you just saying that you prefer to stick with a familiar set of
idiosyncracies for scripting purposes?
Heh. That is
DISKHOG=`echo 1234M /home/USER | sed -e 's;^.*/;;'`
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How about something like:
du -sb ./*|sort -g|tail|sed 's/\.\///'|awk '{print $2}'
to get the names... and then wrap it up in a mail command... it's not a
bash script since it forks a few times, but it's a quick'n'dirty.
Ben
On Mon, 22 Apr 2002, Brian Chabot wrote:
Hey, all -
I'm
On Mon, 22 Apr 2002 [EMAIL PROTECTED] wrote:
I said:
in other words, given: 1234M /home/USER I want USER so as to then turn
around and email that user. (I already have
way of removing non-user directories in /home).
Woo hoo!
Thanks for all the lightning fast help.
I already had most
On Mon, Apr 22, 2002 at 12:16:15PM -0400, Brian Chabot [EMAIL PROTECTED] wrote:
On Mon, 22 Apr 2002 [EMAIL PROTECTED] wrote:
I said:
in other words, given: 1234M /home/USER I want USER so as to then turn
around and email that user. (I already have
way of removing non-user
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In a message dated: Mon, 22 Apr 2002 14:03:32 EDT
Bob Bell said:
Look at the bash man page for '#', '##', '%', and '%%'.
Are these built-ins also available in the real Bourne Shell, and/or ksh?
Or
Yuck, yuck, yuck! It looks like everyone was pointing out ways to
use sed to accomplish this. Now, sed may give you extra
power, but when
writing shell scripts, I prefer to avoid using external commands where
possible. To that extent, consider:
$ foo=1234M /home/USER
$ echo
Mansur, Warren [EMAIL PROTECTED] writes:
Does anyone know how to loop through each line instead, so that the output would be
line 1
line 2
? Thanks.
echo -ne 'line 1\nline 2\n' | while read foo ; do echo $foo ; done
--
John Abreau / Executive Director, Boston Linux Unix
ICQ 28611923
I have not tried it, but what about setting IFS to newline only.
n 22 Apr 2002 at 14:42, Mansur, Warren wrote:
Does anyone know how to loop through each line instead, so that the output would
be
line 1
line 2
? Thanks.
--
Jerry Feldman [EMAIL PROTECTED]
Associate Director
Boston Linux
On Mon, Apr 22, 2002 at 02:15:14PM -0400, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
In a message dated: Mon, 22 Apr 2002 14:03:32 EDT
Bob Bell said:
Look at the bash man page for '#', '##', '%', and '%%'.
Are these built-ins also available in the real Bourne Shell, and/or ksh?
Or
it has a subtle scoping gotcha that drove me nuts the
first time I tripped over it - anybody know what I'm
referring to?
No? Then how about this?
result=badness# init with failure default
spewSomeKindOfOutput | while read input
do
result=goodness
done
echo $result
No? Then how about this?
result=badness# init with failure default
spewSomeKindOfOutput | while read input
do
result=goodness
done
echo $result
What is the output?
badness
Lemme guess. The pipe to the while actually creates a child process, and a child
echo -ne 'line 1\nline 2\n' | while read foo ; do echo $foo ; done
Thanks to all for their answers. I've always wanted to do this but
didn't know how until now. Works like a charm!
Warren
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[EMAIL PROTECTED] (Michael O'Donnell) writes:
it has a subtle scoping gotcha that drove me nuts the
first time I tripped over it - anybody know what I'm
referring to?
No? Then how about this?
result=badness# init with failure default
spewSomeKindOfOutput | while read input
On Mon, Apr 22, 2002 at 05:15:00PM -0400, Mansur, Warren [EMAIL PROTECTED]
wrote:
No? Then how about this?
result=badness# init with failure default
spewSomeKindOfOutput | while read input
do
result=goodness
done
echo $result
What is the output?
On Mon, 22 Apr 2002, at 2:15pm, [EMAIL PROTECTED] wrote:
If they only exist within bash, then I wouldn't advocate their use if
you're goal is portable shell code.
If portability is a concern, depending on the environment, it is sometimes
easier to install the GNU tools everywhere than try to
In general, I try to write my scripts portable so that I can use them on
other platforms. In the past 5 years, I have had jobs with Tru64 Unix, HP-
UX (10.20 and 11.x), Solaris (7 and 8), and Linux (Debian, Red Hat and
SuSE). Most of my personal scripts are small and work across platform. My
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At some point hitherto, Kevin D. Clark hath spake thusly:
result=badness# init with failure default
spewSomeKindOfOutput | while read input
do
result=goodness
done
echo $result
What is the output?
In
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At some point hitherto, Benjamin Scott hath spake thusly:
If portability is a concern, depending on the environment, it is sometimes
easier to install the GNU tools everywhere than try to craft something that
works on all the native tools.
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