sed Pattern to Insert Comma after a character - bash

Question

Add comma after closing bracket } using bash.
Using
sed 's/variable/&,/g;s/,$//'
adds comma after variable, however,
sed 's/}/&,/g;s/,$//'
doesn't work.
Input:
variable "policy_name1" {
description = "abc xyz"
type = string
default = [
"test1"
"test2"
]
}
variable "policy_name2" {
description = "abc xyz"
type = bool
default = false
}
Output:
variable "policy_name1" {
description = "abc xyz"
type = string
default = [
"test1"
"test2"
]
},
variable "policy_name2" {
description = "abc xyz"
type = bool
default = false
}

Answer 1

sed Add a comma after curly bracket, but not on last line:
sed -e '$!s/^ \{4\}}$/&,/'
$!s/ Not on last line replace
^ \{4\}}$ lines begin with 4 space, followed and terminated by }
/&,/ by matched content, followed by ,.
Will render:
variable "policy_name1" {
description = "abc xyz"
type = array
default = [
"test1"
"test2"
]
},
variable "policy_name2" {
description = "abc xyz"
type = bool
default = false
},
variable "policy_name3" {
description = "simple test string..."
type = int
default = 42
}
More complex: Add comma on each lines but not on last for each block:
sed -e ':a;N;/[^{\[(,] *\n/{/\n[ \o11]*[]})]/!s/\n/,\n/};P;D;$!ba'
Could render:
variable "policy_name1" {
description = "abc xyz",
type = array,
default = [
"test1",
"test2"
]
},
variable "policy_name2" {
description = "abc xyz",
type = bool,
default = false
},
variable "policy_name3" {
description = "simple test string...",
type = int,
default = 42
}
:a; Label "a" for furthen branch
N; Merge with next line
/[^{\[(,] *\n/ If buffer contain other than comma or open bracket, followed by newline
{ then do block:
/\n[ \o11]*[]})]/! If NOT buffer contain newline followed by space and other then close bracket
s/\n/,\n/ then place a comma before newline
}; end of block
P; print buffer up to newline
D; delete buffer up to newline
$!ba If not on last line, branch to "a"

Answer 2

Here is what you can do,
#!/usr/bin/env bash
FILENAME="test.tf"
COUNT=`wc -l $FILENAME | awk '{ print $1 }'`
COUNT=`expr $COUNT - 1`
sed "1,$COUNT s/}/},/" "$FILENAME"
I have provided a bash script so that we can avoid the last line in a right way. This script will append a comma whenever it finds an ending curly bracket ( } ) except for when it is last line.