please find an error detected when is used a combination of "xargs" and "grep", arguments {} are not substituted in grep construction:

user@box1:~$ a="i"; echo `echo "inga"|grep -c $a`
1

but was necessary tu use it in combination with xargs:

user@box1:~$ echo "i" | xargs -I{} echo $(echo {} ;a=$(echo {}) ; echo $a ; echo "inga"|grep -c $a)
i i 0
user@box1:~$ echo "i" | xargs -I{} echo $(echo {} ;a=`echo {}` ; echo $a ; echo "inga"|grep -c $a)
i i 0
user@box1:~$ echo "i" | xargs -I{} echo $(echo {} ;a={} ; echo $a ; echo "inga"|grep -c $a)
i i 0
user@box1:~$ echo "i" | xargs  -I{} echo `echo {} ;a={} ; echo $a ; echo "inga"|grep -c $a`
i i 0
user@box1:~$ echo "i" | xargs -I{} echo `echo {} ;a={} ; echo $a ; echo "inga"|grep -c $a`
i i 0
user@box1:~$ echo "i" | xargs -I{} echo `echo {} ;a={} ; echo $a ; echo "inga"|grep -c $a`
i i 0

Thanks,

Sergiu Bordei