Shell Programming and Scripting

hi
iam facing problem regarding sed function. give me reply
with example of sed function. and what to meanings of $# and @
in scripting



please as reply as soon as possible

Sed function has many uses.But mostly is used in replacing text in a file.Following are the examples:

sed 's/text1/text2/' # replaces only 1st instance in a line
sed 's/text1/text2/4' # replaces only 4th instance in a line
sed 's/text1/text2/g' # replaces ALL instances in a line
sed 's/\(.*\)text1\(.*text1\)/\1text2\2/' # replace the next-to-last case
sed 's/\(.*\)text1/\1text2/' # replace only the last case


Also $# means the total number of arguments passed in the script and @ is used as a wild character.