UNIX for Dummies Questions & Answers

hi All,

i have never used sed in Unix environment, but i have one script which is using this following command:

Code:

cat audit_session_rpt_MSP_20140331.lst|sed -n '/Apr 14/!p'| sed -n '/Page/!p'| sed -n '/UserName/!p' |\
egrep -v '^-|^=|^\*'|sed '/^$/d'|sed -e '1,7d' >audit_session_rpt_MSP_20140331.lst_new.lst

Could anyone please interpret what this line of code is actually doing, thanks in advance.

1. opening the file audit_session_rpt_MSP_20140331.lst
2. printing all those lines that doesn't contain "Apr 14" and passing the output to next command
3. printing all those lines that doesn't contain "Page" and passing the output to next command
4. printing all those lines that doesn't contain "UserName" and passing the output to next command
5. Excluding the lines that start with "-" or "=" or "*" and passing the output to next command
6. Excluding the emply lines
7. Deleting first 7 lines
8. and printing the left over lines to audit_session_rpt_MSP_20140331.lst_new.lst