2012年11月8日星期四

Linux Shell语法速查表

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
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