Sed

重要函数说明 #

  • q 提前退出命令，不执行后续命令，也不读入后续行
  • d 删除pattern space(模式空间)中的所有内容，包括换行符
  • D 删除模式空间中的首行，即第一个\n之前的所有内容
  • h 拷贝模式空间中的所有内容到hold space(交换空间)
  • H 追加模式空间中的所有内容到交换空间
  • g 拷贝交换空间中的所有内容到模式空间
  • G 追加交换空间中的所有内容到模式空间
  • n 读取下一个输入行，使用接下来的命令继续对下一行进行处理
  • N 追加下一个输入行到当前模式空间，并改变当前行号
  • p 打印当前行所有模式空间中的内容
  • P 打印当前行模式空间中的首行，即第一个\n之前的所有内容
  • x 将模式空间和交换空间的内容进行交换
  • t label 如果条件满足，则跳转到标签所在地继续执行，若无标签，则到命令末尾
  • b label 直接跳转到标签所在地继续执行，若无标签，则到命令末尾

模式空间和交换空间都属于缓存区

模式空间 (pattern space) #

  • 默认情况下 sed 逐行处理空间
  • 编辑指令支队该空间生效
  • 该空间如无d/D命令，必打印

交换空间/保持空间 (hold space) #

  • 按指令进行存取处理
  • 如需编辑该空间，需交换出去
  • 如需打印，需交换出去

入门例子详解 #

sed的命令参数有： -n -i -e -r

sed的函数参数有: i c a r w y q s n N d D p P h H g G x t b

下面所有的处理均采用该示例文件（exam.txt）内容操作

One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber

命令参数 #

-n参数及p指令 #

  • cat exam.txt | sed ''

类似于直接cat文件不做任何操作

# cat exam.txt | sed ''
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
  • cat exam.txt | sed 'p'

读到第一行的时候接收到 p 指令会把第一行的内容打印出来；第二行One的内容由sed的模式空间自动打印出来的

# cat exam.txt | sed 'p'
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
January February March April May June July August September October November Deccmber
  • cat exam.txt | sed -n 'p'

如只希望采用指令进行打印，不打印模式空间的内容，可以使用 -n参数

# cat exam.txt | sed -n 'p'
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber

-i 参数 #

-i 默认修改文件中的内容

  • sed 's/One/1/' exam.txt > /dev/null; cat exam.txt
# sed -i 's/One/1/' exam.txt > /dev/null; cat exam.txt
1/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
  • sed -i 's/One/1/' exam.txt > /dev/null; cat exam.txt
# sed -i 's/One/1/' exam.txt > /dev/null; cat exam.txt
1/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber

-e 连接多个指令 #

  • sed 's/One/1' 's/Two/2' exam.txt
# sed 's/One/1/' 's/Two/2/' exam.txt
sed: can't read s/Two/2/: No such file or directory
1/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
  • sed -e 's/One/1' -e 's/Two/2' exam.txt
# sed -e 's/One/1/' -e 's/Two/2/' exam.txt
1/2/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber

-r 对正则表达式处理 存疑？ #

  • sed 's/e[2]/ow/' exam.txt

示例目的是把包含两个e的替换为 ow; 如下输出，没有把[2]解析为正则表达式

# sed 's/e[2]/ow/' exam.txt
1/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
  • sed -r 's/e[2]/ow/' exam.txt

函数参数 #

i 插入在匹配到的内容之前添加 #

  • sed '/February/i Spring' exam.txt
# sed '/February/i Spring' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
Spring
January February March April May June July August September October November Deccmber

a 插入在匹配到的内容之后添加 #

  • sed '/February/a Spring' exam.txt
# sed '/February/a Spring' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
Spring

c 匹配到内容整行替换 #

  • sed '/February/c Spring' exam.txt
# sed '/February/c Spring' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
Spring

w 匹配到的内容写入到新文件 #

  • sed '/February/ w exam.tmp' exam.txt
# sed '/February/ w exam.tmp' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
# cat exam.tmp
January February March April May June July August September October November Deccmber

r 读文件 #

  • sed '/One/ r exam.tmp' exam.txt

匹配到One后，读取exam.tmp中的文件打印

# sed '/One/ r exam.tmp' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
January February March April May June July August September October November Deccmber # 这一行为读取exam.tmp文件中的内容
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber

q 退出(包含后面的命令及函数) #

  • sed '2q' exam.txt

表示到第二行的时候就退出

# sed '2q' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday

y 替换字符 #

注意在不同的版本中该命令会不存在；mac上的sed存在该函数。

  • sed 'y/abc/ABC' exam.txt

意思为把 abc 替换为 ABC；注意在不同的系统或版本上的效果可能会存在出入。

➜  ~ sed 'y/abc/ABC/' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
MondAy#TuesdAy#WednesdAy#ThursdAy#FridAy#SAturdAy#SundAy
JAnuAry FeBruAry MArCh April MAy June July August SeptemBer OCtoBer NovemBer DeCCmBer

把 a -> A c->C

➜  ~ sed 'y/[a-c]/[A-C]/' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
MondAy#TuesdAy#WednesdAy#ThursdAy#FridAy#SAturdAy#SundAy
JAnuAry FebruAry MArCh April MAy June July August September OCtober November DeCCmber

= 打印模式空间所在的行数 #

man sed: Write the line number to the standard output followed by a newline character.

  • sed = exam.txt
➜  ~ sed = exam.txt
1
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
2
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
3
January February March April May June July August September October November Deccmber

t 有条件跳转 #

  • sed ':a;s/F/f/;ta' exam.txt

:a 其中a为标签(标签前必须添加冒号，标签名称自己定义) t 后面跟的字符串一定为标签名称。示例的意思为如果碰到 ta(标签)的话回转到开头继续处理不读入下一行，会跳转到标签所在位置继续执行。

匹配到第一行的Four 把 F -> f ，继续在本行替换 F -> f；如匹配不到则不执行t的动作。

# sed ':a;s/F/f/;ta' exam.txt
One/Two/Three/four/five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#friday#Saturday#Sunday
January february March April May June July August September October November Deccmber
  • 如不添加 g 匹配到第一个F后即跳转到第二行处理
# sed 's/F/f/' exam.txt
One/Two/Three/four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#friday#Saturday#Sunday
January february March April May June July August September October November Deccmber

b 无条件跳转 #

  • sed ':label;s/F/f/;/F/blabel' exam.txt

b 为无条件跳转，如果为 sed ':lable;s/F/f;blabel exam.txt'则会陷入死循环，无法跳转出去；这里人为的增加/F/即后续只有再匹配到F的时候才会进行跳转。

# sed ':label;s/F/f/;/F/blabel' exam.txt
One/Two/Three/four/five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#friday#Saturday#Sunday
January february March April May June July August September October November Deccmber
  • sed '/F/ba;s/r/???/;:a;s/^/((/' exam.txt

因为每行都有F，则直接跳转到标签:a 处也就是匹配到 /F/后直接执行 s/^/((/替换操作。

# sed '/F/ba;s/r/???/;:a;s/^/((/' exam.txt
((One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
((Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
((January February March April May June July August September October November Deccmber
  • sed '/xxx/ba;s/r/???/;:a;s/^/((/' exam.txt

操作文件中没一行都没有 xxx 故 ba跳转到标签a不会执行，程序会依次执行；先执行 s/r/??? 操作；:a此时没有跳转失去意义；继续执行后续 s/^/((, 因此结果如下。

# sed '/xxx/b a;s/r/???/; :a;s/^/((/' exam.txt
((One/Two/Th???ee/Four/Five/Six/Seven/Eight/Nine/Ten
((Monday#Tuesday#Wednesday#Thu???sday#Friday#Saturday#Sunday
((Janua???y February March April May June July August September October November Deccmber

n 读入下一行 #

  • sed '1{n; s/o/???/}' exam.txt

1匹配到第一行后执行 n读入下一行内容并把 o替换为??? 输出结果如下。

# sed '1{n; s/o/???/}' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
M???nday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
  • sed -n '1{n;p}' exam.txt

-n 忽略模式空间的内容，仅匹配到第一行后打印下一行的内容。

# sed '1{n;p}' exam.txt
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday

N 通俗将就是把下一行的内容移到到上一行的末尾 #

第一行没有匹配直接输出，第二行匹配到/Monday/后输出模式空间的内容并执行{N; s/\n/\n\n/}即把第三行的内容读取到当前的模式空间，并把 \n 替换为 \n\n

# sed '/Monday/{N;s/\n/\n\n/}' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday

January February March April May June July August September October November Deccmber

p 打印当前行所有模式空间中的内容 #

  • sed -n '2N;p exam.txt

整个命令在执行的过程中2N指对第2行进行N的操作，因为N;p没有放到一个{}中，故p会打印模式空间的内容；匹配到第2行的时候执行N的操作(此时第三行的内容追加到第二行的末尾，指针已经指到第三行) p打印当前模式空间的所有内容，既结果如下。

➜  ~ sed -n '2N;p' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
  • sed -n '2{N;p}' exam.txt

注意：不同的版本对{}支持不同，mac的sed版本不支持 {}; 这里的大括号的作用是对匹配到的内容进行单独操作{}的命令

P 打印当前行模式空间中的首行 #

  • sed -n '2N;P' exam.txt

执行命令的过程为P把第一行的内容打印出来，第二行匹配后执行N的动作，则第二行目前的值为One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten\nMonday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday 再执行P的动作，打印当前模式空间的首行根据\n切分，既打印Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday

➜  ~ sed -n '2N;P' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday

d/D 删除匹配到的行 #

注意：如果模式空间中没有回车符的存在d/D的效果一样均为清空该模式空间的内容,如下面前两个例子。

  • sed '2d' exam.txt
➜  ~ sed '2d' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
January February March April May June July August September October November Deccmber
  • sed '2D' exam.txt
➜  ~ sed '2D' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
January February March April May June July August September October November Deccmber
  • sed 'N;2D' exam.txt
➜  ~ sed 'N;2D' exam.txt
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
  • sed 'N;2d' exam.txt

注意这里不同的版本输出的结果可能不一样

这里没有内容输出，该命令执行的过程采用sedsed调试工具查看如下

# sedsed -d 'N;2d' exam.txt
PATT:One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten$
HOLD:$
COMM:N
PATT:One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten\nMonday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday$
HOLD:$
COMM:2 d
PATT:January February March April May June July August September October November Deccmber$
HOLD:$
COMM:N
January February March April May June July August September October November Deccmber
  • sed 'N;2D;3D' exam.txt
# sedsed -d 'N;2D;3D' exam.txt
PATT:One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten$
HOLD:$
COMM:N
PATT:One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten\nMonday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday$
HOLD:$
COMM:2 D
PATT:Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday$
HOLD:$
COMM:N
PATT:Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday\nJanuary February March April May June July August September October November Deccmber$
HOLD:$
COMM:2 D
PATT:Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday\nJanuary February March April May June July August September October November Deccmber$
HOLD:$
COMM:3 D
PATT:January February March April May June July August September October November Deccmber$
HOLD:$
COMM:N
January February March April May June July August September October November Deccmber
  • sed '$!N;2D;3D' exam.txt

最后一行不做N的操作，最终结果不输出。

g/G 覆盖/追加交换空间中的所有内容到模式空间 #

  • sed 'g' exam.txt

输出三个空行原因是 g把空的交换空间内容覆盖到模式空间，输出打印模式空间内容空。结果如下

PATT:One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten$
HOLD:$
COMM:g
PATT:$
HOLD:$

PATT:Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday$
HOLD:$
COMM:g
PATT:$
HOLD:$

PATT:January February March April May June July August September Octo\
ber November Deccmber$
HOLD:$
COMM:g
PATT:$
HOLD:$
  • sed 'G' exam.txt

G 追加交换空间的内容到模式空间，这个例子中输出结果相当于是每行末尾添加一个空行。

# sed 'G' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten

Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday

January February March April May June July August September October November Deccmber
  • seq 3 | sed 'N;G'
1
2

3
  • seq 4 | sed 'N;G'
1
2

3
4

h/H 拷贝/追加模式空间的内容到交换空间 #

  • sed '1h;3g' exam.txt
# sed '1h;3g' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
  • sed '1{h;d};3G' exam.txt
# sed '1{h;d};3G' exam.txt
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
  • sed 'h;3g' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
  • sed '1h;3g' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
  • sed 'H;3g' exam.txt
# sed 'H;3g' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday

One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber
  • sed '1h;3x' exam.txt
# sed '1h;3x' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
  • sed '1h;3{g;G}' exam.txt
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
  • sed '2{x;p;x}' exam.txt

在指定的行上面添加一个空行

One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten

Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber

进阶实例讲解 #

文件中有/如何处理简单 #

正常使用sed进行替换操作如 sed 's/One/1/' exam.txt 如果要匹配的是/则可以指定默认的符号，这里指定的为:(可以把这里的冒号默认理解为原来的/), 两个:之间的内容为要替换的内容。

  • 将程序里以 // 注释修改为 /*... */注释
    • sed 's://\(.*\):/* \1 */:' test.go
    • sed -r 's://(.*):/* \1 */:' test.go
    • sed -r 's#//(.*)#/* \1 */#' test.go

如何输出奇数行 #

  • sed 'n;d' exam.txt
  • sed -n 'p;n' exam.txt
  • sed '$!N;P;d' exam.txt

将偶数行附加在奇数行 #

  • sed '$!N;s/\n/ /' exam.txt
    • 推荐这种方法
    • $!N 不对最后一行做N
  • sed -n 'h;n;H;g;s/\n/ /;p' exam.txt

重温 N, $!N 的用法 #

  • 在不熟悉N的运作模式下，请勿直接使用
  • 一般情况下，用 $!N 绝对没错
  • N一旦失败，代表着sed的结束

打印或删除匹配的上一行 #

  • sed -n '/hello/{g;p};h 打印匹配hello的上一行
  • sed -n 'N;\n.*hello/!P;D' 删除匹配hello的上一行

数字格式化 #

  • sed -r ':a;s/(.*[0-9])([0-9]{3})/\1,\2/;ta'
# echo 1234567 | sed -r ':a;s/(.*[0-9])([0-9]{3})/\1,\2/;ta'
1,234,567

# echo 1234567 | sed --debug -r ':a;s/(.*[0-9])([0-9]{3})/\1,\2/;ta'
SED PROGRAM:
  :a
  s/(.*[0-9])([0-9]{3})/\1,\2/
  t a
INPUT:   'STDIN' line 1
PATTERN: 1234567
COMMAND: :a
COMMAND: s/(.*[0-9])([0-9]{3})/\1,\2/
MATCHED REGEX REGISTERS
  regex[0] = 0-7 '1234567'
  regex[1] = 0-4 '1234'
  regex[2] = 4-7 '567'
PATTERN: 1234,567
COMMAND: t a
COMMAND: :a
COMMAND: s/(.*[0-9])([0-9]{3})/\1,\2/
MATCHED REGEX REGISTERS
  regex[0] = 0-4 '1234'
  regex[1] = 0-1 '1'
  regex[2] = 1-4 '234'
PATTERN: 1,234,567
COMMAND: t a
COMMAND: :a
COMMAND: s/(.*[0-9])([0-9]{3})/\1,\2/
PATTERN: 1,234,567
COMMAND: t a
END-OF-CYCLE:
1,234,567

重温t,b 标签的用法 #

# cat num.txt
1
2
1
3
1
1
  • 按行算，把第偶数个出现的1改为0
    • sed '/1/{:a;n;s/1/0/;tb;ba;:b}' num.txt
# sed '/1/{:a;n;s/1/0/;tb;ba;:b}' num.txt
1
2
0
3
1
0

关键点 #

  • t/b都表示跳转，区别在于t为有条件跳转
  • t与s匹配同用，当替换成功则跳转
  • 使用b请自带条件，否则易死循环

重温d/D的用法 #

关键点 #

  • 当模式空间无\n, d/D完全一样
  • N/P/D用处大，D删除后如果模式空间还有内容，会继续进行循环
  • 使用d删除后，直接跳到下一行

打印带有hello的段落 #

  • sed '/./{H;$!d};x;/hello/!d;s/.//'
  • awk -v RS= '/hello/'

删除文件最后10行内容 #

  • sed ':a;$d;N;2,10ba;P;D'

神奇的用法 ~ #

  • 如何每隔2行输出1行，比如1，4，7，10
# seq 10 | sed -n '1~3p'
1
4
7
10

# seq 10 | sed -n '0~3p'
3
6
9

变态的 addr1/addr2 #

关键点 #

  • 0,/addr2/和1,/addr2/类似，不同点在于是否addr2匹配了文件的第一行
  • 当addr1匹配成功后，一直到匹配上/addr2/后才会关闭，且后续行不再打开
  • 如果/addr2/一直无法匹配，则开关一直打开，规则一直执行到结束
  • 如果addr2是行号，一旦该行大于addr2，即刻关闭开关，不执行后面的命令
# cat test
a1
a2
a3
a4
a5

# sed '0,/a/{s/a/ax/}' test
ax1
a2
a3
a4
a5

# sed '1,/a/{s/a/ax/}' test
ax1
ax2
a3
a4
a5

# sed '1,/z/{s/a/ax/}' test
ax1
ax2
ax3
ax4
ax5

综合实例讲解 #

反转单词 #

  • echo 'how are you' | sed -r 'G;:a;s/(\w+) ?(\n.*)/\2 \1/;ta;s/\n //'
  • echo 'how are you' | awk '{for(i=NF;i>0;i--)printf("%s ",$i);print ""}'
    • you are how

只将第二次出现的1替换为0 #

# cat num
1
2
1
3
1
  • sed '0,/1/b;0,/1/{/1/s/1/0/}' num
  • awk '/1/{a++;if(a==2)gsub(/1/,0,$0)}1' num
#sed '0,/1/b;0,/1/{/1/s/1/0/}' num 
1
2
0
3
1

实际案例 #

如下一个log文件，内容现在需要输出打印所有syncing字段记录，且带上时间。思路为把时间作为数组下标，带有syncing的作为key。

# cat log
Sun Mar 13 17:42:39 CST 2016
10.171.21.45 manual
10.170.2.45 load
Sun Mar 13 18:12:19 CST 2016
10.191.23.12 ping
10.233.82.2 syncing
10.34.11.11 loading
Sun Mar 13 18:32:49 CST 2016
10.33.32.11 syncing
10.32.32.32 manual
10.10.10.10 syncing
  • awk '/CST/{c=$0;a[c]}/syncing/{a[c]=a[c]$0"\n"}END{l=asorti(a,b);for(i=1;i<=l;i++)if(a[b[i]])printf b[i]"\n"a[b[i]]}' log
  • sed -n '/CST/h;/syncing/{x;//!p;g;p}' log
  • sed -n '/CST/h;/syncing/{x;/syncing/!p;g;p}' log
  • sed -n '/CST/h;/syncing/{x;/^$/!p;g;p;s/.*//;h}' log
Sun Mar 13 18:12:19 CST 2016
10.233.82.2 syncing
Sun Mar 13 18:32:49 CST 2016
10.33.32.11 syncing
10.10.10.10 syncing
  • sed -n '/CST/h;/syncing/{x;p;g;p;s/.*//;h}' log
# sed -n '/CST/h;/syncing/{x;p;g;p;s/.*//;h}' log 
Sun Mar 13 18:12:19 CST 2016
10.233.82.2 syncing
Sun Mar 13 18:32:49 CST 2016
10.33.32.11 syncing

10.10.10.10 syncing

学习资料 #

sedsed解释 #

  • -d 打开调试模式
  • PATT Pattern Space的内容
  • HOLD Hold Space的内容
  • COMM sed执行的命令
  • $ PATT与HOLD的结束符
  • ... 不以任何标识符开头的是最终输出的结果
➜  ~ sedsed -d 'N;2D' exam.txt
PATT:One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten$
HOLD:$
COMM:N
PATT:One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten$
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday$
HOLD:$
COMM:2 D
PATT:Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday$
HOLD:$
COMM:N
PATT:Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday$
January February March April May June July August September October November Deccmber$
HOLD:$
COMM:2 D
PATT:Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday$
January February March April May June July August September October November Deccmber$
HOLD:$
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber

或直接使用

# sed --debug 'N;2D' exam.txt
SED PROGRAM:
  N
  2 D
INPUT:   'exam.txt' line 1
PATTERN: One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten
COMMAND: N
PATTERN: One/Two/Three/Four/Five/Six/Seven/Eight/Nine/Ten\nMonday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
COMMAND: 2 D
PATTERN: Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
COMMAND: N
PATTERN: Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday\nJanuary February March April May June July August September October November Deccmber
COMMAND: 2 D
END-OF-CYCLE:
Monday#Tuesday#Wednesday#Thursday#Friday#Saturday#Sunday
January February March April May June July August September October November Deccmber