Bash中的多行输入，单引号内的子shell术语

Question

我想用约。 Bash中的以下构造用于在PostgreSQL的配置文件中生成行：

T0=$(date +%s)
cat > $PGDATA/recovery.conf <<EOL
recovery_target_inclusive = true
recovery_target_time = \'$(date -d @$T0 "+%Y-%m-%d %H:%M:%S %Z")\'
recovery_target_timeline = latest
EOL

我目前收到此输出：

recovery_target_inclusive = true
recovery_target_time = \'2018-01-04 12:47:44 UTC\'
recovery_target_timeline = latest

如何获得不会丢失单引号的版本？

Answer 1

简单：不要逃避引号。

cat > $PGDATA/recovery.conf <<EOL
recovery_target_inclusive = true
recovery_target_time = '$(date -d @$T0 "+%Y-%m-%d %H:%M:%S %Z")'
recovery_target_timeline = latest
EOL