Question

So I have this sed command applied on $1 wich is a file
what I’d like to know is how sed evaluates all the slash, backslash
succession and what does any character in the pattern mean

sed '/^\/\*/d/.*\*\//d' $1

as far as I know

'/^ ....../d' 

deletes some pattern at the begining of line (considering the second d)

-what does the first d stand for, what about the dot and the / or /\ (unescape chars?)

could please someone explain this to me please ?

Answer 1

This is actually two sed commands back to back:

/^\/\*/d
/.*\*\//d

^ matches start of line, \/ matches a literal forward-slash, \* matches a literal asterisk. (Since forward-slash and asterisk are “meta-characters”, they need to be escaped with a backslash to match literally.)

.* matches any sequence of characters, \* matches a literal asterisk again, \/ matches a literal slash again.

Put it all together, and what this does is to delete C-style comments, but only if they appear at the start of a line:

/* This will go away */This will stay