Ubuntu 16.04系统默认最大打开文件数为1024个

代码证明

1 #include <stdio.h>
2 #include <sys/types.h>
3 #include <fcntl.h>
4 #include <stdlib.h>
5 #include <unistd.h>
6
7 int main(int argc,char *argv[]){
8
9     int fd;
10     char name[1024];
11     int i = 0;
12     while(1){
13         sprintf(name,"file%d",++i);
14         fd = open(name,O_CREAT,0777); //超过最大打开数时再打开会出错，返回-1
15         if (fd == -1){
16             exit(1);
17         }
18         printf("%d ",i);
19     }
20     return 0;
21 }

运行代码

#gcc -o haha open.c
#./haha

修改最大打开文件数

# ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 7674
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 7674
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

# ulimit -n 4096

# cat /proc/sys/fs/file-max
97267