5-1-4-shell：字符串处理进阶--sed篇

处理方式：逐行处理

处理类型：增删改查

文件demo: test.txt

this is a test str.
is 1 is 2 is 3 is 4 is 5 is 6 is 7 is 8
1234
qwer

-i 参数直接修改文件

插入选中行下一行文本, 开始标识字符 a\, 前置为选中行索引

sed '1a\abcd' test.txt

结果：
"
this is a test str. 
abcd
is 1 is 2 is 3 is 4 is 5 is 6 is 7 is 8
1234
qwer
"

插入选中行上一行文本, 开始标识字符 i\, 前置为选中行索引

sed '1i\abcd' test.txt

结果：
"
abcd 
this is a test str.
is 1 is 2 is 3 is 4 is 5 is 6 is 7 is 8
1234
qwer
" 

删除指定一行, 标识字符 d, 前置为行索引

sed '2d' test.txt

结果：
"
this is a test str.
1234
qwer
"

删除指定多行, 标识字符 d, 前置为行索引区间

sed '2,3d'  test.txt

结果
"
this is a test str.
qwer
"

删除指定行到末尾, 标识字符 d, 前置为行索引区间, $ 标识末尾

sed '3,$d'  test.txt

结果：
"
this is a test str.
is 1 is 2 is 3 is 4 is 5 is 6 is 7 is 8
"

替换  开始符s/, 结束符 /g

sed 's/is/at/g' test.txt

结果：
"
that at a test str. 
at 1 at 2 at 3 at 4 at 5 at 6 at 7 at 8
1234
qwer
"

查找包含字符的行, 参数-n , 结束符 /g

sed -n '/r/g' test.txt

结果：
"
1  this is a test str.
4  qwer
"