如何在多行变量的每一行前面添加文本？

Question

我打印所有变量及其值

echo "$val"

 mapreduce.map.memory.mb,3584
 mapreduce.map.java.opts,-Xmx2560m
 mapreduce.reduce.memory.mb,3584
 mapreduce.reduce.java.opts,-Xmx2560m
 mapreduce.task.io.sort.mb,1280

如何在每行的开头附加单词 - type_config

所以输出如下

 type_config,mapreduce.map.memory.mb,3584
 type_config,mapreduce.map.java.opts,-Xmx2560m
 type_config,mapreduce.reduce.memory.mb,3584
 type_config,mapreduce.reduce.java.opts,-Xmx2560m
 type_config,mapreduce.task.io.sort.mb,1280

Answer 1

$ echo "$val" | sed 's/^/type_config,/g'

输出：

type_config,mapreduce.map.memory.mb,3584
type_config,mapreduce.map.java.opts,-Xmx2560m
type_config,mapreduce.reduce.memory.mb,3584
type_config,mapreduce.reduce.java.opts,-Xmx2560m
type_config,mapreduce.task.io.sort.mb,1280