sed - have several pass on the same file in one sed script

Question

In sed documentation, we read that "sed works by making only one pass over the input(s)".

I would like to write a sed script (to be run like this : sed -f my_script.sed), that performs several operations including on the operations that were performed earlier in the script.

Is it possible to perform a second (or n-th) pass on the edited stream content ?

e.g. :

• initial stream content :

titi

• stream content after first pass :

/titi/ i (
/titi/ a )

$ cat test.txt
(
titi
)

• after another pass :

s/(/{/g
s/)/}/g

I would like the output to be

$ cat test.txt
{
titi
}

This is just an example to show that i'd like to perform stream editions that have effects on previous commands inside a single .sed script.

Answer 1

sed only gets one pass over the input stream. This is specifically stated in the man page (at least, on Fedora 33, anyway).

Whenever I have to do something like this, I pipe the output of sed into a second instance of sed to do the subsequent edits.