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条件语句 if (expression) { statement; statement; ... ... } if (expression) { statement; } else { statement2; } if (expression) { statement1; } else if (expression1) { statement2; } else { statement3; } 循环语句 C语言:while、do/while、for、break、continue Examples: 一.命令行方式...
List information about the FILEs (the current directory by default). Sort entries alphabetically if none of -cftuvSUX nor --sort is specified. Mandatory arguments to long options are mandatory for short options too. -a, --all do not ignore entries starting with . -A, --almost-all do not...
-u True if the user id is set on a file -w True if the file is writable -x True if the file is an executableExamplesIn this section, we'll see couple of examples of the 'if/elif/else' statement.Exampe #1:#!/bin/bash # b.sh if [ "$#" -gt 0 ] then echo "There are $...
-e :实现多个选项间的逻辑or 关系 -E:扩展的正则表达式 -f FILE:从FILE获取PATTERN匹配 -F :相当于fgrep -i --ignore-case #忽略字符大小写的差别。 -n:显示匹配的行号 -o:仅显示匹配到的字符串 -q:静默模式,不输出任何信息 -s:不显示错误信息。
awk、grep、sed是linux操作文本的三大利器,合称文本三剑客,也是必须掌握的linux命令之一。三者的功能都是处理文本,但侧重点各不相同,其中属awk功能最强大,但也最复杂。grep更适合单纯的查找或匹配文本,sed更适合编辑匹配到的文本,awk更适合格式化文本,对文本进行较复杂格式处理。
1 switch语句和shell中的case很像，就不在演示了switch(expression) {case VALUE1 or /REGEXP/:statement1; case VALUE2 or /REGEXP2/: statement2;...; default: statementn}5.2 break和continue---奇数相加[root@along ~]# awk 'BEGIN{sum=0;for(i=1;i<=100;i++){if(i%2==0)continue;sum+...
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> set password = password('Passwd123'); Query OK, 0 rows affected, 1 warning (0.00 sec) //开启远程访问权限 mysql> use mysql; Reading table information for completion of table and column names You...
For both directives, if the condition following the “if statement” is false, the preprocessor does not pass any of the program text between the #if and the next #endif to the compiler. If you plan to look at any C code, you’d better get used to this. 条件语句。你可以使用#ifdef...
131 ie a "while" in a do-statement or an "else" in an if-statement, like 132 this: 133 134 do { 135 body of do-loop 136 } while (condition); 137 138 and 139 140 if (x == y) { 141 .. 142 } else if (x > y) { 143 ... 144 } else { 145 ... 146 } 147 148...