AWK操作字符串的截取
AWK操作字符串的截取
AWK操作字符串的截取
对于awk和Bash来说，他们使用的是不同的string索引系统；
bash的第一个字符从0开始记录；
awk的第一个字符从1开始记录；
#012345678 ------------Bash
#123456789 -------------Awk
以下是案例说明：
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[root@Slave02 shell]# vi substring-extraction.sh
#!/bin/bash
String=23skidoo1
echo ${String:2:4}
echo |awk '{ print substr("'"${String}"'",3,4) }'
exit 0
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"substring-extraction.sh" [New] 8L, 108C written
[root@Slave02 shell]# sh substring-extraction.sh
skid
skid
[root@Slave02 shell]#
使用变量的前缀来匹配前面声明过的所有变量；
如：
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[root@Slave02 shell]# xyz23=watever
[root@Slave02 shell]# xyz24=asdf
[root@Slave02 shell]# echo "
a=${!xyz*}"
a=xyz23 xyz24
[root@Slave02 shell]# echo "a=${!xyz@}"
a=xyz23 xyz24
[root@Slave02 shell]#
抛骰子游戏；
SPOTS=6 -----取模为6，范围在0-5
die1=0
die2=0
------------2个变量名称，保证每个平面选择的数字记录相同
let "die1 = $RANDOM % $SPOTS +1"
let "die2 = $RANDOM % $SPOTS +1"
let "throw = $die1 + $die2"
echo "Throw of the dice = $throw"
echo
exit 0
以下验证结果：
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Random number greater than 200 --- 25552
Throw of the dice = 5
[root@Slave02 shell]#
[html]
random number less than 500 --- 0
Random number greater than 200 --- 9765
Throw of the dice = 2
[root@Slave02 shell]#
[html]
Random number greater than 200 --- 31180
Throw of the dice = 10
[root@Slave02 shell]#
[root@Slave02 shell]# sh random2.sh
Random number between 0 and 1 = 0.246062
[root@Slave02 shell]# sh random2.sh
Random number between 0 and 1 = 0.619153
[root@Slave02 shell]# sh random2.sh
Random number between 0 and 1 = 0.619153
[root@Slave02 shell]# sh random2.sh
Random number between 0 and 1 = 0.619153
[root@Slave02 shell]# sh random2.sh
Random number between 0 and 1 = 0.619153
[root@Slave02 shell]# sh random2.sh
Random number between 0 and 1 = 0.201116
[root@Slave02 shell]# cat random2.sh
#!/bin/bash
AWKSCRIPT='{ srand(); print rand() }' -srand中伪随机的计算
echo -n "Random number between 0 and 1 = "
echo | awk "$AWKSCRIPT"
exit 0
[root@Slave02 shell]#
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