[root@localhost ~]# seq 5 | sed 's/^/@/'

@1

@2

@3

@4

@5

插入单引号

[root@localhost ~]# seq 5 | sed "s/^/\'/"

'1

'2

'3

'4

'5

 [root@localhost ~]# df -h | grep "/$" | awk ' {print $5}' | sed 's/%//'

36

[root@localhost ~]# df -h | grep "/$" | awk ' {print +$5}'

36

[root@localhost ~]# head /etc/passwd > test.txt

[root@localhost ~]# while read line

> do

> list=$line

> done < test.txt

[root@localhost ~]# for line in $(cat test.txt)

> do

> echo $line

> done

[root@localhost script]# ifconfig | grep -Eo '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+'

192.168.0.210

192.168.0.255

255.255.255.0

127.0.0.1

255.0.0.0

[root@localhost script]# ifconfig | grep -oP '(\d+\.){3}\d+' 

192.168.0.210

192.168.0.255

255.255.255.0

127.0.0.1

255.0.0.0

#使用Perl正则

[root@localhost script]# ps aux | grep crond

root      1056  0.0  0.0 117212  1280 ?        Ss   Feb10   0:21 crond

root     10776  0.0  0.0 103240   856 pts/0    S+   18:42   0:00 grep crond

[root@localhost script]# ps aux | grep [c]rond

root      1056  0.0  0.0 117212  1280 ?        Ss   Feb10   0:21 crond

#[c]rond可以匹配crond，但不会匹配自身。

[root@localhost script]# cat time.txt

09:00:01,more aaa bbb ccc

09:00:02,more aaa bbb ccc

09:00:03,more aaa bbb ccc

09:00:04,more aaa bbb ccc

09:00:05,more aaa bbb ccc

[root@localhost script]# awk  -F ",| " '{print $1,$3,$4,$5}' time.txt

09:00:01 aaa bbb ccc

09:00:02 aaa bbb ccc

09:00:03 aaa bbb ccc

09:00:04 aaa bbb ccc

09:00:05 aaa bbb ccc

[root@localhost script]# for ip in 192.168.0.{1..255}

> do

> ping $ip -c2 &>/dev/null

> if [ $? -eq 0 ];then

>   echo $ip is alive

> fi

> done

192.168.0.1 is alive

192.168.0.2 is alive

192.168.0.5 is alive

192.168.0.6 is alive

192.168.0.7 is alive

#这种方法效率低

[root@localhost script]# fping -a -g 192.168.0.1/24 2>/dev/null

192.168.0.1

192.168.0.2

192.168.0.5

192.168.0.6

192.168.0.10

192.168.0.17

#fping命令效率比较高，-a是检查存活的系统，-g 192.168.0.1/24 产生扫描的目标列表 。

[root@localhost script]# nmap -v -sP 192.168.0.1/24 | grep -B1 "up"

#nmap也比较快

[root@localhost script]# awk '{x+=$2+$3;a[NR]=$2+$3} END{y=x/NR;for(i in a){if(y<a[i]) z++} print z}' number.txt

4

下例是一个更详解的awk脚本实现

#!/bin/awk -f

BEGIN {}

{

  x+=$2+$3

  a[NR]=$2+$3

  print $0,a[NR]

}

END {

  y=x/NR

  printf "The sum: %d\n", x

  printf "The average: %d\n",y

  for ( i in a )

  {

   if (y<a[i])

    z++

  }

  printf "The counter: %d\n",z

}

[root@localhost script]# ./tt.sh number.txt

1 2 4 8 6

5 8 0 2 8

3 1 8 3 9

7 0 2 7 2

3 9 1 0 10

3 2 7 4 9

The sum: 44

The average: 7

The counter: 4

[root@localhost script]# cat n1.txt

1

2

3

4

5

[root@localhost script]# ./ta.sh n1.txt

1 + 2 = 3

2 + 3 = 5

3 + 4 = 7

4 + 5 = 9

[root@localhost script]# cat ta.sh

#!/bin/awk -f

{

  a[NR]=$1

}

END{

  for (i=2;i<=NR;i++)

  {

   printf "%d + %d = %d \n",a[i-1],a[i],a[i]+a[i-1]

  }

}

[root@localhost script]# for i in `seq 3`;do echo $i;done

1

2

3

[root@localhost script]# for i in {1..3};do echo $i;done

1

2

3

[root@localhost script]# for ((i=1;i<=3;i++));do echo $i;done

1

2

3

[root@localhost script]# awk '{a[$1]+=$3} END {for ( i in a) print i,a[i]}' conn.txt

20120102 5202

20120103 1040

20120105 3600

20120107 1200

20120101 2020

[root@localhost script]# cat conn.txt

20120101 MAXConnection: 1000

20120102 MAXConnection: 1002

20120105 MAXConnection: 1600

20120101 MAXConnection: 1020

20120103 MAXConnection: 1040

20120102 MAXConnection: 1200

20120105 MAXConnection: 2000

20120107 MAXConnection: 1200

20120102 MAXConnection: 3000

[root@localhost ~]# HOST=1.1.1.1

[root@localhost ~]# echo "127.0.0.1"|sed  s/127.0.0.1/"$HOST"/

1.1.1.1

[root@localhost ~]# cat -n  /etc/passwd | sed -n "$var1,$var2 p"

     1  root:x:0:0:root:/root:/bin/bash

     2  bin:x:1:1:bin:/bin:/sbin/nologin

     3  daemon:x:2:2:daemon:/sbin:/sbin/nologin

[root@localhost ~]# echo $var1 $var2

1 3

[root@localhost ~]# cat -n /var/log/messages | sed -n '40,42p'

    40  May 12 06:45:33 localhost nagios:

    41  May 12 07:45:33 localhost nagios:

42  May 12 08:45:33 localhost nagios:

[root@localhost ~]# cat -n /var/log/messages | awk 'NR==40,NR==42'

[root@localhost ~]# cat -n /var/log/messages | head -42 |  tail -3

[root@localhost ~]# echo "aaaa123bbbb456,.?ccc789" | sed 's/[^[:digit:]]*//g'

123456789

[root@localhost ~]# echo "tom and jerry" | sed -r 's/\b([a-zA-Z])/\u\1\u/g'

Tom And Jerry

#文本内容如下

[root@localhost script]# cat python.txt

Python is powerful... and fast;

plays well with others;

runs everywhere;

is friendly & easy to learn;

is Open.

#对行进行迭代

[root@localhost script]# cat line.sh

#!/bin/bash

#Filename:Line.sh

while read line

do

echo $line

done < $1

[root@localhost script]# ./line.sh python.txt

#对单词进行迭代，文件中包含标点符号，可以用sed替换掉

[root@localhost script]# sed 's/[[:punct:]]//g' python.txt > python_nopun.txt

#如果要保留标点，则需要将单词和标点使用空格分隔开

[root@localhost script]# sed s/[[:punct:]]/" & "/g python.txt

#

[root@localhost script]# cat word.sh

#!/bin/bash

#Filename:word.sh

while read line

do

  for word in $line

  do

    echo $word

  done

done <$1

[root@localhost script]# ./word.sh python_nopun.txt

Python

is

powerful

and

fast

……

#对字符进行迭代

[root@localhost script]# cat letter.sh

#!/bin/bash

#Filename:letter.sh

while read line

do

  for word in $line

  do

    for ((i=0;i<${#word};i++))

    do

      echo ${word:i:1}

    done

  done

done <$1

[root@localhost script]# ./letter.sh python_word.txt

P

y

t

h

o

n

i

s

#从字符串中提取字符

${string:start_position:no_of_characters}

[root@localhost script]# str="abcde"

[root@localhost script]# echo ${str:0:1}

a

[root@localhost script]# echo ${str:1:1}

b