一 API
1. bsearch
NAME
bsearch - binary search of a sorted array
SYNOPSIS
#include <stdlib.h>
void *bsearch(const void *key, const void *base,
size_t nmemb, size_t size,
int (*compar)(const void *, const void *));
2. isdigit
isdigit()
checks for a digit (0 through 9).
3. 数组赋值 int arr[MAX] = {[0 ... (MAX - 1)] = 0};
4. qsort
NAME
qsort, qsort_r - sort an array
SYNOPSIS
#include <stdlib.h>
void qsort(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *));
void qsort_r(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *, void *),
void *arg);
二 命令
1. 查看config：zcat /proc/config.gz 或 cat /boot/config_xxx
2. 查看sysctrl -a 可配置项
3. sudo sysctl -w fs.inotify.max_user_watches="65535000" 设置文件描述符watch个数
4. sudo systemctl enable ssh 默认开启ssh服务
5. 打包logs目录成多个包，每个最大为10MB：tar cjf - logs/ |split -b 10m - logs.tar.bz2.
解包：cat logs.tar.bz2.a* | tar xj