awk - Append a string after a multiple line match in bash -
i need sed or awk command print line after multiple line match in bash. example having file input:
admin: users: - user1 - user2 read_only: users: - user3 write_only: users: - user4 access_only: users: - user5 - user6 ..i need have output:
admin: users: new user - user1 - user2 read_only: users: - user3 write_only: users: - user4 access_only: users: - user5 - user6 the regex should match first 2 lines admin: users: , append new user line.
how this? should use sed or awk? how? thank you
with sed
delimit block between /^[a-z_]\+:/ , /^$/, somme process in 1 block:
sed -e $'/^admin:/,/^$/{/users:/a\ newuser\n}' this written:
newuser="user2017" sed -e "/^admin:/,/^$/{ /users:/a\ - $newuser }" (by using double quotes, use variable commandline or script)
this render:
admin: users: - user2017 - user1 - user2 read_only: users: - user3 ... or pure bash...
myadduser () { local crt= line; while ifs= read line; echo "$line"; [ "$line" ] && { [ "${line:0:1}" != " " ] && crt=${line%:} || { [ "${line//*([: ])}" = "users" ] && [ "$crt" = "${2:-admin}" ] && printf " - %s\n" $1 } }; done } which used:
myadduser newadminuser <file.txt admin: users: - newadminuser - user1 - user2 read_only: users: - user3 ... or optional second argument:
myadduser newwriteuser write_only admin: users: - user1 - user2 read_only: users: - user3 write_only: users: - newwriteuser - user4 access_only: users: - user5 - user6 but please,
read sobrique's fine answer!
with perl or python prototyping using c finalized programmation, may find apropriate libraries.
using of libraries in shell done too.
1st admin userperl -myaml -e 'undef$/;$s = load(<>);say@{$s->{admin}->{users}}[0];' perl -myaml -e 'undef$/;$s = load(<>);say scalar@{$s->{admin}->{users}};' 
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