创建linux分区时，必须创建swap和根分区
登陆linux时，一个具有唯一进程Id号的shell将被调用，这个ID是什么? 是PID
哪个变量是用来定义shell的全局变量的？ 是export
awk while循环:
{ i = 1
while (i <= $3) {
printf(" %.2f
", $1 * (1 + $2) ^ i)
i = i + 1
}
}
awk if循环:
END { if (n > 0)
print n, "employees, total pay is", pay,
"average pay is", pay/n
else
print "no employees are paid more than $6/hour"
}
awk使输出的结果对齐
awk '{print}' 3.txt
{ sum = 0 for (i = 1; i <= NF; i = i + 1) sum = sum + $iprint sum}
BEGIN { FS = " " # make tab the field separator
printf("%10s %6s %5s %s
",
"COUNTRY", "AREA", "POP", "CONTINENT")
}
{ printf("%10s %6d %5d %s
", $1, $2, $3, $4)
area = area + $2
pop = pop + $3第二章 AWK 语言 22
}
END { printf("
%10s %6d %5d
", "TOTAL", area, pop) }
如果将 countries 作为输入, 将出将是
COUNTRY AREA POP CONTINENT
USSR 8649 275 Asia
Canada 3852 25 North America
China 3705 1032 Asia
USA 3615 237 North America
Brazil 3286 134 South America
India 1267 746 Asia
Mexico 762 78 North America
France 211 55 Europe
Japan 144 120 Asia
Germany 96 61 Europe
England 94 56 Europe
TOTAL 25681 2819