Bash EOF块在EOF块中可能吗？

Question

我正尝试在一个文件中写入一个包含它自己的EOF块的块。这在bash中是可行的吗？

cat > terragrunt.hcl <<'EOF' 
# Automatically generated from script $(basename $0)

# Generate the AWS provider block
generate "provider" {
  path      = "provider.tf"
  if_exists = "overwrite_terragrunt"
  contents  = <<EOF
# Terragrunt root config
provider "aws" {
  # Only these AWS Account IDs may be operated on by this template
  allowed_account_ids = ["${local.account_id}"]
  region = "${local.infra_region}"
  version = "${local.customer_vars.locals.aws_provider_version}"
}
EOF
}

# Automatically generated from script $(basename $0)
EOF

正如预期的那样，它失败了：

❯ ./example.sh 
./example.sh: line 17: syntax error near unexpected token `}'
./example.sh: line 17: `}'

处理它的最佳解决方案是什么？

Answer 1

您所称的"EOF块“实际上被称为"Here Document" (通常缩写为"heredoc")，而字符串"EOF”实际上可以是您喜欢的任何“单词”。

heredoc包含所有内容，直到它匹配的分隔符为止，所以嵌套两个heredocs只需要选择两个不同的分隔符：

cat > terragrunt.hcl <<'ENDTERRAGRUNT' 
# Automatically generated from script $(basename $0)

# Generate the AWS provider block
generate "provider" {
  path      = "provider.tf"
  if_exists = "overwrite_terragrunt"
  contents  = <<ENDROOTCONFIG
# Terragrunt root config
provider "aws" {
  # Only these AWS Account IDs may be operated on by this template
  allowed_account_ids = ["${local.account_id}"]
  region = "${local.infra_region}"
  version = "${local.customer_vars.locals.aws_provider_version}"
}
ENDROOTCONFIG
}

# Automatically generated from script $(basename $0)
ENDTERRAGRUNT