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转载自: http://blog.csdn.net/kwiner/archive/2009/04/05/4049640.aspx

虽然学过 Linux Shell 编程，但由于编写 Shell 脚本的机会实在是比较少 ( 通常在项目初期搭建开发环境时编写得比较多一些 ) ，所以一些语法久而久之就会忘了，一个简单的语法去翻书效率实在是慢，所以就个人整理了一个表格，由于我用的编程语言是 C/C++ ，所以在编程的时候往往脑海里面首先浮现的是用 C 语言怎么去编写它，所以我干脆拿 C 语言的语法来和 Shell 编程的语法作个对比表，这样查起来就方便了，哈：

要实现的功能	C 语言编程	Linux Shell 脚本编程
程序 / 脚本的参数传递	int main(int argc , char** argv ) { if (argv != 4) {     printf ( “Usage: %s arg1 arg2 arg3”, argv [0] );     return 1; } printf (“arg1:%s\n”,argv[1]); printf (“arg2:%s\n”,argv[2]); printf (“arg3:%s\n”,argv[3]); return 0; }	#!/bin/sh if [ $# -lt 3 ]; then     echo "Usage: `basename $0` arg1 arg2 arg3" >&2     exit 1 fi echo "arg1: $1" echo "arg2: $2" echo "arg3: $3" exit 0
	int main(int argc , char** argv ) {     int i ; for (i =1; i <=argc;i ++) { printf (“arg:%s\n”,argv [i ]); } return 0; }	#!/bin/sh while [ $# -ne 0 ] do     echo "arg : $1"     shift done
逻辑 / 数值运算	if (d == 0)	if [ "$D" -eq "0" ] ; then
	if (d != 0)	if [ "$D" -ne "0" ] ; then
	if (d > 0)	if [ "$D" -gt "0" ] ; then
	if (d < 0)	if [ "$D" -lt "0" ] ; then
	if (d <= 0)	if [ "$D" -le "0" ] ; then
	if (d >= 0)	if [ "$D" -ge "0" ] ; then
字符串比较	if (strcmp (str,”abc ”)==0) { }	if [ "$STR" != "abc " ]; then fi
输入和输出	scanf (“%d”,&D );	read D
	printf ( “%d”, D);	echo –n $D
	printf ( “%d”,D );	echo $D
	printf ( “Press any to continue...”); char ch =getchar (); printf ( “\nyou pressed: %c\n”, ch );	#!/bin/sh getchar () { SAVEDTTY=`stty -g` stty cbreak dd if=/dev/tty bs =1 count=1 2> /dev/null stty -cbreak stty $SAVEDTTY } echo -n "Press any key to continue..." CH=`getchar ` echo "" echo "you pressed: $CH"
		read D <&3
程序 / 脚本的控制流程	if (isOK ) {     //1 } else if (isOK2) {     //2 } else {     //3 }	if [ isOK ]; then     #1 elif [ isOK2 ]; then     #2 else     #3 fi
	switch (d) { case 1: printf (“you select 1\n”); break; case 2: case 3: printf (“you select 2 or 3\n”); break; default: printf (“error\n”); break; };	case $D in 1) echo "you select 1"     ;; 2|3) echo "you select 2 or 3"     ;; *) echo "error"     ;; esac
	for (int loop=1; loop<=5;loop++) {      printf ( “%d”, loop); }	for loop in 1 2 3 4 5 do     echo $loop done
	do {     sleep(5); } while( !isRoot );	IS_ROOT=`who | grep root` until [ "$IS_ROOT" ] do     sleep 5 done
	counter=0; while( counter < 5 ) { printf ( “%d\n”, counter); counter++; }	COUNTER=0 while [ $COUNTER -lt 5 ] do echo $COUNTER     COUNTER=`expr $COUNTER + 1` done
	while (1) { }	while : do done
	break;	break 或 break n ， n 表示跳出 n 级循环
	continue;	continue
函数与过程的定义	void hello() {     printf ( “hello\n” ); } … // 函数调用 hello();	hello() {     Echo “hello” } 或者 function hello() {     Echo “hello” } … # 函数调用 hello
函数的参数和返回值	int ret = doIt (); if (ret == 0) {     printf ( “OK\n” ); }	doIt if [ “$?” –eq 0 ] ; then echo “OK” fi 或者 RET = doIt if [ “$RET” –eq “0” ] ; then echo “OK” fi
	int sum(int a,int b) { return a+b ; } int s = sum(1,2); printf (“the sum is: %d\n”, s);	sum() {     echo -n "`expr $1 + $2`" } S=`sum 1 2` echo "the sum is: $S"
	bool isOK () { return false; } if (isOK ) {     printf ( “YES\n” ); } else {     printf ( “NO\n” ); }	isOK () {     return 1; } if isOK ; then     echo "YES" else     echo "NO" fi