Shell，换行带空格的文本块
在SHELL编程中，如果使用for循环操作一个带空格的文本块，如果不做任何处理，则会根据空格切分循环项，而不是根据换行切换。
显然，这不是我们需要的。
在SHELL中，可以通过设定【IFS】特殊变量，来自定义循环项的边界。
具体的实现如下所示：
注意：
这里的代码是在AIX系统[……]
Category Archives: SHELL
Shell：文件是否存在
代码：
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[root@mysql-me ~]# pwd /root [root@mysql-me ~]# ls -ltr | grep test_me -rw-r--r-- 1 root root 0 Jul 5 00:18 test_me [root@mysql-me ~]# [root@mysql-me ~]# if [ -f "/root/test_me" ]; then echo "exsist"; rm -rf /root/test_me; echo "delete"; else echo "not exsist"; fi exsist delete [root@mysql-me ~]# [root@mysql-me ~]# ls -ltr | grep test_me [root@mysql-me ~]# [root@mysql-me ~]# if [ -f "/root/test_me" ]; then echo "exsist"; rm -rf /root/test_me; echo "delete"; else echo "not exsist"; fi not exsist [root@mysql-me ~]# [root@mysql-me ~]# |
其他的还有：
#!/bin/sh
myPath=”/var/log/httpd/”
myFile=”/var /log/httpd/access.log”
#这里的-x 参数判断$[……]
Shell，除法运算
代码：
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[root@mysql-me python]# printf "%.5f\n" `echo "scale=5;1/3"|bc` 0.33333 [root@mysql-me python]# [root@mysql-me python]# echo "scale=5;a=1/3;if(length(a)==scale(a)) print 0;print a;"|bc 0.33333[root@mysql-me python]# [root@mysql-me python]# [root@mysql-me python]# awk 'BEGIN{printf "%.2f\n",'5/6'}' 0.83 [root@mysql-me python]# |
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Done。
Shell，日期类值的运算
代码：
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[root@zabbix-me script]# cat calc_datestr.sh str_date="$1" str_operation="$2" str_howmuch="$3" str_result="" echo "======================" echo "Source Date String: $str_date" echo "Operation: $str_operation" echo "How much = $str_howmuch" echo "======================" str_result=`date -d "$str_operation$str_howmuch day $str_date" +%F` echo "Result is: $str_result" echo "======================" echo "Finished." [root@zabbix-me script]# [root@zabbix-me script]# sh calc_datestr.sh 2017-06-30 + 1 ====================== Source Date String: 2017-06-30 Operation: + How much = 1 ====================== Result is: 2017-07-01 ====================== Finished. [root@zabbix-me script]# [root@zabbix-me script]# sh calc_datestr.sh 2017-06-30 - 1 ====================== Source Date String: 2017-06-30 Operation: - How much = 1 ====================== Result is: 2017-06-29 ====================== Finished. [root@zabbix-me script]# [root@zabbix-me script]# |
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Done。
SHELL，用函数改变公共变量
代码：
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[root@oracle-cluster-3 shell]# cat define_variable_in_func.sh var_1="1" echo "Before change value is: [$var_1]" function change_value() { eval func_variable="$1" func_new_value="$2" #"`eval echo $func_variable`"="$func_new_value" eval $func_variable=\"${func_new_value}\" } change_value "var_1" "$1" echo "After change value is: [$var_1]" [root@oracle-cluster-3 shell]# [root@oracle-cluster-3 shell]# sh define_variable_in_func.sh "hello world" Before change value is: [1] After change value is: [hello world] [root@oracle-cluster-3 shell]# [root@oracle-cluster-3 shell]# sh define_variable_in_func.sh "hello world(abcd)" Before change value is: [1] After change value is: [hello world(abcd)] [root@oracle-cluster-3 shell]# |
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Done。