Bash: Replace each occurrence of string in file with next value from array - bash

Question

I have an .yml file with three address entries and some other data, and an array containing three new addresses to replace these with
file.yml:
[...]
- address: s1.example.com
user: ubuntu
role: storage
- address: w1.example.com
user: ubuntu
role: worker
- address: w2.example.com
user: ubuntu
role: worker
[...]
array:
addr[0]: storage.domain.com
addr[1]: worker1.domain.com
addr[2]: worker2.domain.com
expected result:
[...]
- address: storage.domain.com
user: ubuntu
role: storage
- address: worker1.domain.com
user: ubuntu
role: worker
- address: worker2.domain.com
user: ubuntu
role: worker
[...]
I'm using sed, as I would like to write the new lines directly to the original file
I have tried a number of times, but the array incrementing always fails
Attempt 1
sed -i "s/- address: .*/- address: ${addr[$i]}/g" file.yml
This seems to exclusively write the first item in the array:
- address: storage.domain.com
[...]
- address: storage.domain.com
[...]
- address: storage.domain.com
[...]
Attempt 2
if (grep -e "- address:" file.yml); then
sed -i "s/- address: .*/- address: ${addr[$i]}/g"
((i++))
fi
This seems to grep all results at the same time, and forwards nothing to sed as I haven't figured that one out yet.
Output:
- address: s1.example.com
- address: w1.example.com
- address: w2.example.com
sed: no input files

Answer 1

Recently I started doing this with similar jobs:
Print all array members with some separator, ex. :. Put this as the first input to sed.
The first line (ie. the array members printed with some separator) are put into hold space
Then for each the - address: found:
I copy the hold space into pattern space, extract the first element of the array and append it with - address :. And print.
And remove the first element from hold space
The script below:
# replicate input
cat <<EOF >file.yml
[...]
- address: s1.example.com
user: ubuntu
role: storage
- address: w1.example.com
user: ubuntu
role: worker
- address: w2.example.com
user: ubuntu
role: worker
[...]
EOF
addr[0]=storage.domain.com
addr[1]=worker1.domain.com
addr[2]=worker2.domain.com
# the sed script
sed -nE '
1{
# hold the first line with array members separated with :
H
# don't print anything
d
}
# if the line is address
/- address: .*/{
g
s/\n//
# remove all except first array member from hold space
s/:.*//
# prepend it with _- address_
s/^/- address: /
# remove the first member from hold space
x
s/[^:]*://
x
}
# print the output
p
' <( IFS=':'; printf "%s\n" "${addr[*]}"; ) file.yml
and the same oneliner:
sed -n '1{;H;d};/- address: .*/{g;s/\n//;s/:.*//;s/^/- address: /;x;s/[^:]*://;x};p' <( IFS=':'; printf "%s\n" "${addr[*]}"; ) file.yml
will output:
[...]
- address: storage.domain.com
user: ubuntu
role: storage
- address: worker1.domain.com
user: ubuntu
role: worker
- address: worker2.domain.com
user: ubuntu
role: worker
[...]

Answer 2

#! /bin/bash
# initialise the array the way you want
addr[0]="storage.domain.com"
addr[1]="worker1.domain.com"
addr[2]="worker2.domain.com"
awk -F: -v addr="${addr[*]}" ' BEGIN{count=0 ; split(addr, addr_array, " ") }
{
if( $1 ~ /address/ ) {
for(i=1;i<=NF-1;++i){
printf "%s:", $i
}
printf "%s\n", addr_array[++count]
}
else
{
print
}
}' file.yml
If you want to overwrite the original file,
addr[0]="storage.domain.com"
addr[1]="worker1.domain.com"
addr[2]="worker2.domain.com"
gawk -i inplace -F: -v addr="${addr[*]}" ' BEGIN{count=0 ; split(addr, addr_array, " ") }
{
if( $1 ~ /address/ ) {
for(i=1;i<=NF-1;++i){
printf "%s:", $i
}
printf "%s\n", addr_array[++count]
}
else
{
print
}
}' file.yml

Answer 3

One possible solution is as follows:
addr=(storage.domain.com worker1.domain.com worker2.domain.com)
i=0
line_count=1
while IFS= read -r line; do
if [[ $line == *"- address:"* ]]; then
sed -i "${line_count}s/- address: .*/- address: ${addr[i]}/" file.yml
i=$((i+1))
fi
line_count=$((line_count+1))
done < file.yml
Above script iterates through the file, line by line and then replace the matching line with the content of the array.

Answer 4

This might work for you (GNU sed):
printf ": %s\n" "${addr[#]}" |
sed '/address:/R /dev/stdin' ymlFile |
sed '/address:/{N;s/:.*:/:/}'
Print the addr array out to stdout so that each address is on a separate line.
In the first invocation of sed, insert each address on a separate line following the regexp address:.
In the second invocation of sed remove the old addresses.