sed to insert line just before end of range

tshikose · 12-24-2021, 06:22 AM

Quote:

Originally Posted by Turbocapitalist

Neat.

Sed scripts, like all scripting languages, can be annotated:

Code:

#!/usr/bin/sed -nf 

/3/!{                   # if line does not contain a 3 
        p;              # print
        d;              # clear and jump to the beginning
};

:loop;                  # land here

N;                      # append next line to pattern space

/7/{                    # if the line contains a 7
        s//&\nFOOBAR/p; # & means the found pattern, in this case the line
        d;              # clear and jump to the beginning
};

$!bloop;                # if not at the end, then jump to marker above

The -f is important.

I know but I prefer to have it as a one liner.
I use a long sed with -i and several -e to have it modified in one shot.

shruggy · 12-24-2021, 07:09 AM

Well, while this is no INI file, the structure is sufficiently similar, so crudini may actually help in this case, too.

Code:

$ cat postgresql.conf
# This is a comment
log_connections = yes
log_destination = 'syslog'
search_path = '"$user", public'
shared_buffers = 128MB
$ crudini --set --output=- postgresql.conf '' log_connections no
# This is a comment
log_connections = no
log_destination = 'syslog'
search_path = '"$user", public'
shared_buffers = 128MB
$ crudini --set --output=- postgresql.conf '' datestyle "'iso, mdy'"
# This is a comment
log_connections = yes
log_destination = 'syslog'
search_path = '"$user", public'
shared_buffers = 128MB
datestyle = 'iso, mdy'

OTOH, Augeas is packaged for EL8 and provides a lens for posgresql.conf. I'd look into doing this with augtool. There are also Python and Ruby bindings in python3-augeas and ruby-augeas, respectively. And it's supported by Puppet, too.

To give you a perspective on Augeas in RHEL, here is the relevant discussion at Red Hat Customer Portal.

TBH, now I'm perplexed just as pan64 was above.

Quote:

Originally Posted by pan64

I don't understand it at all. That range specification is completely pointless here. (ok, the real code can be different)

Code:

sed "/$i/ i FFOOBBAARR"

With postgresql.conf being a flat configuration file without any nested structures, I don't see the point in matching a range inside it. Matching just a line would do the same.

MadeInGermany · 12-26-2021, 03:19 AM

In standard (default print) mode you can use
b
rather than
{p;d;}

Because sed does not have variables you must use a loop.
Another attempt (yet untested, and using standard sed code):

Code:

sed '
/3/!b
:L
n
/7/!bL
i\
FOOBAR
'