Misterious command output

[Javi]

Hi,

Take the follow commands (debian sid bash shell):

n=0;
while [ $n -lt 1000 ];
do
ldapsearch -x -h ldap -b 'dc=company,dc=com' uid |
tee /var/tmp/ldap-search.$n |
grep ^uid |
awk '{print $2}' |
sort |
{ tee a | head -1 ; tail -9 a; rm a; } |
md5sum
((n++));
done | sort | uniq -c

Result:
15 01755713a62aa7e6c22a56e3b1d8f140 -
2 bcdfba835b152d70f78018b1bf9c05b1 -
983 c5b4e951bb8a73809be2a4b69789f831 -

And all ldapsearch output are the same:
md5sum /var/tmp/ldap-search.* | uniq -w32
bded37d641d33fb9b47b58e47c8a1a1a /var/tmp/ldap-search.0

If I delete "{tee a | head -1; tail -9 a ; rm a; } " from the command
then I get the correct output (all the outputs is the same):
1000 b0ffe3bcb3569e81e6e9a0f319e462a5 -

Do you know why could be this issue ?

Thanks in advanced

[Stephane CHAZELAS]

2008-03-24, 09:03(-07), Javi:
[...]

> Take the follow commands (debian sid bash shell):
>
> n=0;
> while [ $n -lt 1000 ];
> do
> ldapsearch -x -h ldap -b 'dc=company,dc=com' uid |
> tee /var/tmp/ldap-search.$n |
> grep ^uid |
> awk '{print $2}' |
> sort |
> { tee a | head -1 ; tail -9 a; rm a; } |

[...]

tee may be killed by a SIGPIPE if "head" terminates before tee
manages to write everything.

You could do:

{ cat > a; head -1 a; tail -9 a; rm a; }

Or use sed '1!d' instead of "head -1" as it doesn't exit until
the whole input has been read.

--
Stéphane

[Javi]

Thank you very much.