I want to copy a given text file (on macOS or Unix in general) to stdout where to any { and : character a newline is added.
I tried
sed “s/{/{\n/g” myfile.txt
Just for the curly bracket character, but this doesn’t seem to work.
Do I need to install the GNU version of sed for this? And if so, how can I add newlines to both characters { and : in one go?
Just backslash the literal newline.
catalina$ sed 's/[{:]/\
> /'g <<\_
> hello: this{is} an example{of}something: poo
> there
> _
hello
this
is} an example
of}something
poo
there
If you would like to replace the matched character with itself, include & in the replacement.
catalina$ sed 's/[{:]/&\
/'g <<\_
> hello: this is {another} example
> more: newlines!
> here
> _
hello:
this is {
another} example
more:
newlines!
here
There are many variations around how exactly this works in exactly which sed version, though I believe the above should work everywhere. GNU sed adds some conveniences, like the ability to use \n as an abbreviation for newline, but this is not portable. In general, I would suggest moving to Awk or Perl if you need to use non-portable sed features.
Sometimes you can also use shell features like sed $'s/[{:]/\\\n/g' but this (for now) is Bash-specific, and probably not an improvement in terms of legibility. (In brief, $'...' offers a single-quoted string with "C string" semantics, meaning the shell converts \n to a literal newline, \t to a literal tab, etc; you then also need to escape a literal backslash with another backslash to prevent the shell from interpreting it as something else. This shell feature is proposed to be included in a future POSIX version, so it will ultimately be portable to any POSIX-conformant shell, but don't hold your breath.)
In case it's not obvious, [{:] is a regex character class which matches a single character out of the enumeration between the square brackets.