Replace special characters with sed

Question

I have to replace special characters using shell, so i use sed but i have some mistakes that i don't understand.

<%_ by [@, ("_" = dash)
_%> by ]

for the first 2 characters my synthax is : sed -i y/\<%\/\]\/ test.htm it works, but here how can i add the dash character ? The second should be this way sed -i y/\%>\/\]\/ but i have this mistake bash: /]/: is a folder can you help me please

Answer 1

I'm not sure what you are trying to replace (with a - or _ in the first case) but this works fine for me:

$ echo "<%_" | sed 's/<%_/_/'
_
$ echo "<%_" | sed 's/<%_/-/'
-
$ echo "_%>" | sed 's/_%>/\]/'
]

It looks like you are escaping the regex identifiers (the /).

Answer 2

You need to quote the argument, and use the s command to perform string substitution. You can use the -e option to supply multiple command expressions.

sed -i -e 's/<% /[@/' -e 's/ %>/]/' filename