sed: command garbled - when executed with $variables

Shell Programming and Scripting
1

I have got a file job_tree.lst , which contains 1 line as below

$ cat job_tree.lst
ABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0

I want to get a child job string 3 characters offset from the parent job string (i.e. ABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0 available in job_tree.lst)
The command I am using in shell script to carry out the above task is as below

grep $parent job_tree.lst | tail -1 |sed -e 's*'${parent_job_rep}''' '${child_job_rep}''

but it's producing an error �SED command: Command Garbled error�

Pl see the test below what I have done in the command prompt

$ cat job_tree.lst
ABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0

$ echo $parent
ABC_D_EQ_XXXXX_YYYY_PRD_UX

$ echo $child_job_rep
XYZ_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0

$ echo $parent_job_rep
ABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0

$ grep $parent job_tree.lst | tail -1 |sed -e 's*'${parent_job_rep}''' '${child_job_rep}''
sed: command garbled: s*ABC_D_EQ_XXXXX_YYYY_PRD_UX

But when I give literals in place of substitution variables , it's working see below

$ grep $parent job_tree.lst | tail -1 |sed -e 'sABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0 XYZ_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0*'
XYZ_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0

Can the experts help?

Thanks

2 
echo 'ABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0' | sed -e "s|$parent_job_rep|$child_job_rep|g"

XYZ_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0

3

echo 'ABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0' | sed -e "s|$parent_job_rep|$child_job_rep|g"

This is working , but when I add grep... instaed of echo , sed does not substitute the string with child_job_rep.See the result below. Any clues ?

$ grep $parent job_tree.lst | tail -1|sed -e "s|$parent_job_rep|$child_job_rep|g"
ABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0

4

devtakh,
Any suggestions for the above issue?
Thanks

5 
$ child_job_rep='XYZ_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 I
N 13412850/0'

$ parent_job_rep='ABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50
IN 13412850/0'

$ grep $parent file| tail -1
ABC_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0

$ grep $parent ftree | tail -1 | sed -e "s|$parent_job_rep|$child_job_rep|g"
XYZ_D_EQ_XXXXX_YYYY_PRD_UX 05/08/2009 05:47 05/08/2009 05:50 IN 13412850/0