orangeの博客

发表于 更新于 分类于 Valine：
本文字数： 2.2k 阅读时长 ≈ 2 分钟

版本切换工具篇

JENV管理JDK

jdk全称”Java Development Kit“，指的是Java语言的软件开发工具包，主要用于移动设备、嵌入式设备上的java应用程序的开发。jdk是java开发的核心，包括了JRE（Java运行环境）运行时类库、JVM（Java虚拟机）。

一般，我们需要用到基于Java虚拟机的操作服务时，需要有JDK的环境，这样的Java有两个特点（Write once, run anywhere）：

  • 易于移植：只需要有Java的虚拟机（JDK）环境，即可运行Java程序。
  • 需要平台有Java虚拟机支持：Java程序有所限制，需要有Java环境支持

大部分程序开发者，或者普通用户，都有了解过JDK的配置。但是：

  • Linux服务器上怎么配置JDK呢？
  • 能否实现多版本JDK同时配置安装呢？

本次教程，就在Linux（ubuntu系统）上安装多版本JDK，并使用Jenv管理JDK。

安装思路

常规（传统）安装

我们通常安装JDK是：

  • Centos系统使用yum包管理器安装/Ubuntu使用apt包管理器安装，然后直接使用。
  • 上传源码包、解压源码包、在环境变量文件中追加JAVA_HOME然后source重载配置后使用。

前卫安装

在前面常规（传统）安装的前提下，追加Jenv的配置，实现JDK的切换：

确定使用OpenJDK和JDK的版本之后，使用ZuluJDK（一个OpenJDK的发行版本）

安装JDK8
1
2
3
4
5
6
# wget 下载源码包
root@VM-4-12-ubuntu:~# wget https://cdn.azul.com/zulu/bin/zulu8.66.0.15-ca-jdk8.0.352-linux_x64.tar.gz
# 创建源码包保存目录
root@VM-4-12-ubuntu:~# mkdir /JDK
# 解压源码包至保存目录
root@VM-4-12-ubuntu:~# tar -xzvf zulu8.66.0.15-ca-jdk8.0.352-linux_x64.tar.gz -C /JDK/
1
2
3
4
5
6
7
# 配置JAVA_HOME
root@VM-4-12-ubuntu:~# vim .bashrc
# JAVA环境变量配置
JAVA_HOME=/JDK/jdk8
CLASSPATH=$JAVA_HOME/lib/
PATH=$PATH:$JAVA_HOME/bin/
export PATH JAVA_HOME CLASSSPATH
1
2
# 重载配置
root@VM-4-12-ubuntu:~# source ~/.bashrc 
1
2
3
4
5
# 查看版本（JDK1.8就是JDK8）
root@VM-4-12-ubuntu:~# java -version
openjdk version "1.8.0_352"
OpenJDK Runtime Environment (Zulu 8.66.0.15-CA-linux64) (build 1.8.0_352-b08)
OpenJDK 64-Bit Server VM (Zulu 8.66.0.15-CA-linux64) (build 25.352-b08, mixed mode)

多版本JDK管理

安装JENV

Jenv项目地址

1
2
# 使用git下载jenv源码到用户目录下的.jenv文件夹
root@VM-4-12-ubuntu:~# git clone https://github.com/jenv/jenv.git ~/.jenv
1
2
3
4
5
# 配置环境变量
root@VM-4-12-ubuntu:~# vim .bashrc
# Jenv配置环境变量
export PATH="$HOME/.jenv/bin:$PATH"
eval "$(jenv init -)"
1
2
# 重载配置(会出现“jenv has been updated, process to refresh plugin links”这句话，说明配置成功)
root@VM-4-12-ubuntu:~# source ~/.bashrc

现在jenv就可以使用了：

1
root@VM-4-12-ubuntu:~# jenv help

切换JDK

1
2
# 查看当前安装的JDK版本
root@VM-4-12-ubuntu:~# jenv versions
1
2
# 局部JDK11
root@VM-4-12-ubuntu:~# jenv local 11
1
2
# 全局JDK11
root@VM-4-12-ubuntu:~# jenv global 11

管理JDK

有时候，jenv的add扫描，扫描的内容过多怎么办呢？比如，我只添加了JDK8、JDK11,怎么会有这么多版本JDK：

1
2
3
4
5
6
7
8
9
root@VM-4-12-ubuntu:~# jenv versions
* system (set by /root/.jenv/version)
  11
  11.0
  11.0.17
  1.8.0.352
  1.8
  1.8.0.352
  zulu64-1.8.0.352

这个时候也很简单，使用remove命令即可：

1
2
root@VM-4-12-ubuntu:~# jenv remove zulu64-1.8.0.352
root@VM-4-12-ubuntu:~# jenv remove 1.8
1
2
3
4
root@VM-4-12-ubuntu:~# jenv versions
  system
  11.0.17
* 1.8.0.352 (set by /root/.jenv/version)

NVM管理Node.js

发表于 更新于 分类于 Valine：
本文字数： 13k 阅读时长 ≈ 12 分钟

[toc]

free

检测系统内存Mem和交换空间swap

1
2
3
4
root@raspbian:~# free -h
              total        used        free      shared  buff/cache   available
Mem:          7.7Gi       405Mi       6.8Gi        17Mi       481Mi       7.1Gi
Swap:         1.0Gi          0B       1.0Gi

total:内存总大小

used:已用

free:空闲

available:可用

swap:交换

hdparm

检查磁盘性能，指定-t选项检查磁盘（评估硬盘的读取效率(不经过磁盘cache)），指定-T 平估硬盘快取的读取效率

1
2
3
4
5
6
7
8
9
10
11
12
root@raspbian:~# hdparm -t /dev/mmcblk0

/dev/mmcblk0:
 HDIO_DRIVE_CMD(identify) failed: Invalid argument
 Timing buffered disk reads: 132 MB in  3.02 seconds =  43.65 MB/sec

root@raspbian:~# hdparm -tT /dev/mmcblk0

/dev/mmcblk0:
 Timing cached reads:   1914 MB in  2.00 seconds = 958.37 MB/sec
 HDIO_DRIVE_CMD(identify) failed: Invalid argument
 Timing buffered disk reads: 132 MB in  3.03 seconds =  43.63 MB/sec

查找命令在哪个软件包

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
# 比如说我需要iostat
root@raspbian:~# apt-cache search iostat
dstat - versatile resource statistics tool
ganglia-modules-linux - Ganglia extra modules for Linux (IO, filesystems, multicpu)
ifstat - InterFace STATistics Monitoring
nicstat - print network traffic statistics
pcp-import-iostat2pcp - Tool for importing data from iostat into PCP archive logs
r-cran-epi - GNU R epidemiological analysis
r-cran-epibasix - GNU R Elementary Epidemiological Functions
r-cran-kmi - GNU R Kaplan-Meier Multiple Imputation
r-cran-rms - GNU R regression modeling strategies by Frank Harrell
sysstat - system performance tools for Linux

# 挑一个吧
root@raspbian:~# apt-get install sysstat

iostat

1
2
3
4
5
6
7
8
root@raspbian:~# iostat
Linux 5.10.78-Release-OPENFANS+20211111-v8 (raspbian)   09/04/2022      _aarch64_       (4 CPU)
#cpu使用情况
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.75    0.00    0.45    0.09    0.00   98.71
#磁盘使用情况
Device             tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
mmcblk0           2.71       136.86        24.05    1074327     188817

-c:显示cpu使用情况

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
# 2秒5次列出cpu情况
root@raspbian:~# iostat -c 2 5
Linux 5.10.78-Release-OPENFANS+20211111-v8 (raspbian)   09/04/2022      _aarch64_       (4 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.75    0.00    0.44    0.08    0.00   98.73


avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.37    0.00    0.25    0.00    0.00   99.38


avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.13    0.00    0.13    0.00    0.00   99.75


avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.25    0.00    0.12    0.00    0.00   99.62


avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.12    0.00    0.38    0.00    0.00   99.50

-d:磁盘使用情况

1
2
3
4
5
6
7
8
9
10
11
12
# 2秒3次
root@raspbian:~# iostat -d 2 3
Linux 5.10.78-Release-OPENFANS+20211111-v8 (raspbian)   09/04/2022      _aarch64_       (4 CPU)

Device             tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
mmcblk0           2.53       124.41        22.50    1074327     194285

Device             tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
mmcblk0           3.00         0.00        16.00          0         32

Device             tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
mmcblk0           1.00         0.00        36.00          0         72

-x:指定磁盘设备名称

1
2
3
4
5
6
7
8
9
10
11
12
# 指定/dev/mmcblk0磁盘设备2秒3次
root@raspbian:~# iostat -dx /dev/mmcblk0 2 3
Linux 5.10.78-Release-OPENFANS+20211111-v8 (raspbian)   09/04/2022      _aarch64_       (4 CPU)

Device            r/s     w/s     rkB/s     wkB/s   rrqm/s   wrqm/s  %rrqm  %wrqm r_await w_await aqu-sz rareq-sz wareq-sz  svctm  %util
mmcblk0          1.45    1.00    118.12     21.71     0.77     1.31  34.61  56.73    5.45   10.22   0.02    81.67    21.76   2.42   0.59

Device            r/s     w/s     rkB/s     wkB/s   rrqm/s   wrqm/s  %rrqm  %wrqm r_await w_await aqu-sz rareq-sz wareq-sz  svctm  %util
mmcblk0          0.00    0.00      0.00      0.00     0.00     0.00   0.00   0.00    0.00    0.00   0.00     0.00     0.00   0.00   0.00

Device            r/s     w/s     rkB/s     wkB/s   rrqm/s   wrqm/s  %rrqm  %wrqm r_await w_await aqu-sz rareq-sz wareq-sz  svctm  %util
mmcblk0          0.00    7.50      0.00     34.00     0.00     1.00   0.00  11.76    0.00    7.00   0.05     0.00     4.53   0.80   0.60

sar

1
2
3
4
5
6
7
8
9
10
root@raspbian:~# sar -u 2 5 
Linux 5.10.78-Release-OPENFANS+20211111-v8 (raspbian)   09/04/2022      _aarch64_       (4 CPU)

10:32:27 AM     CPU     %user     %nice   %system   %iowait    %steal     %idle
10:32:29 AM     all      1.38      0.00      1.00      0.00      0.00     97.62
10:32:31 AM     all      7.50      0.00      1.38      0.00      0.00     91.12
10:32:33 AM     all      0.25      0.00      0.87      0.00      0.00     98.88
10:32:35 AM     all      0.25      0.00      0.00      0.00      0.00     99.75
10:32:37 AM     all      0.50      0.00      0.13      0.00      0.00     99.37
Average:        all      1.97      0.00      0.67      0.00      0.00     97.35

lsof

查看端口服务，-i查看对应端口服务

1
2
3
4
5
6
root@raspbian:~# lsof -i:22
COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
sshd      834 root    3u  IPv4  26704      0t0  TCP *:ssh (LISTEN)
sshd      834 root    4u  IPv6  26706      0t0  TCP *:ssh (LISTEN)
BT-Panel 1147 root   13u  IPv4  43447      0t0  TCP raspbian:11716->raspbian:ssh (ESTABLISHED)
sshd     4694 root    3u  IPv4  42753      0t0  TCP raspbian:ssh->raspbian:11716 (ESTABLISHED)

netstat

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
root@raspbian:~# netstat 
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      6 10.71.10.25:8101        10.68.65.140:5937       ESTABLISHED
tcp        0    176 raspbian:ssh            raspbian:11716          ESTABLISHED
tcp      160      0 raspbian:11716          raspbian:ssh            ESTABLISHED
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags       Type       State         I-Node   Path
unix  2      [ ]         DGRAM                    43560    /run/user/0/systemd/notify
unix  3      [ ]         DGRAM                    15265    /run/systemd/notify
unix  16     [ ]         DGRAM                    15276    /run/systemd/journal/dev-log
unix  2      [ ]         DGRAM                    15282    /run/systemd/journal/syslog
unix  7      [ ]         DGRAM                    15291    /run/systemd/journal/socket
unix  2      [ ]         DGRAM                    24174    @00001
unix  3      [ ]         STREAM     CONNECTED     22269    
unix  2      [ ]         DGRAM                    27827    
unix  2      [ ]         DGRAM                    22165    
unix  3      [ ]         STREAM     CONNECTED     21099    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     22163    
unix  2      [ ]         DGRAM                    22143    
unix  2      [ ]         DGRAM                    22139    
unix  3      [ ]         STREAM     CONNECTED     22433    
unix  3      [ ]         STREAM     CONNECTED     22432    
unix  3      [ ]         STREAM     CONNECTED     19284    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     26018    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     26017    
unix  2      [ ]         DGRAM                    25873    
unix  3      [ ]         STREAM     CONNECTED     25871    
unix  3      [ ]         STREAM     CONNECTED     25870    
unix  3      [ ]         STREAM     CONNECTED     18705    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     27250    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     25862    
unix  3      [ ]         STREAM     CONNECTED     30216    /run/containerd/containerd.sock.ttrpc
unix  3      [ ]         STREAM     CONNECTED     32039    
unix  3      [ ]         STREAM     CONNECTED     18236    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     29646    /run/containerd/containerd.sock.ttrpc
unix  3      [ ]         STREAM     CONNECTED     20201    
unix  3      [ ]         STREAM     CONNECTED     32038    
unix  3      [ ]         STREAM     CONNECTED     20289    
unix  3      [ ]         STREAM     CONNECTED     29570    /run/containerd/s/efda43ab145a8b986f0fd3455c3b2956d5def686d2807c67031ad6563f9958db
unix  3      [ ]         STREAM     CONNECTED     31928    
unix  3      [ ]         STREAM     CONNECTED     24063    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     20541    
unix  3      [ ]         STREAM     CONNECTED     27836    
unix  2      [ ]         DGRAM                    16406    
unix  3      [ ]         STREAM     CONNECTED     20777    
unix  3      [ ]         STREAM     CONNECTED     43564    
unix  3      [ ]         STREAM     CONNECTED     21400    
unix  3      [ ]         STREAM     CONNECTED     20542    
unix  2      [ ]         DGRAM                    14168    
unix  3      [ ]         STREAM     CONNECTED     21401    
unix  2      [ ]         DGRAM                    18426    
unix  3      [ ]         STREAM     CONNECTED     44613    /run/systemd/journal/stdout
unix  2      [ ]         DGRAM                    18148    
unix  2      [ ]         DGRAM                    43546    
unix  3      [ ]         STREAM     CONNECTED     24181    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     18312    
unix  3      [ ]         STREAM     CONNECTED     18430    
unix  2      [ ]         DGRAM                    41797    
unix  3      [ ]         STREAM     CONNECTED     28070    
unix  3      [ ]         STREAM     CONNECTED     18313    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     21097    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     17383    /run/systemd/journal/stdout
unix  3      [ ]         DGRAM                    15267    
unix  3      [ ]         STREAM     CONNECTED     25700    
unix  3      [ ]         STREAM     CONNECTED     43538    
unix  3      [ ]         STREAM     CONNECTED     17927    
unix  3      [ ]         STREAM     CONNECTED     25701    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     41806    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     18147    
unix  3      [ ]         STREAM     CONNECTED     16734    
unix  3      [ ]         STREAM     CONNECTED     20214    /run/systemd/journal/stdout
unix  3      [ ]         DGRAM                    15266    
unix  3      [ ]         STREAM     CONNECTED     14309    /run/systemd/journal/stdout
unix  3      [ ]         DGRAM                    43561    
unix  3      [ ]         STREAM     CONNECTED     27733    
unix  2      [ ]         DGRAM                    16736    
unix  3      [ ]         STREAM     CONNECTED     26790    /var/run/dbus/system_bus_socket
unix  3      [ ]         DGRAM                    16739    
unix  2      [ ]         DGRAM                    43549    
unix  2      [ ]         STREAM     CONNECTED     41786    
unix  3      [ ]         STREAM     CONNECTED     25802    
unix  3      [ ]         DGRAM                    16740    
unix  3      [ ]         DGRAM                    43562    
unix  3      [ ]         STREAM     CONNECTED     26994    /run/systemd/journal/stdout
unix  2      [ ]         DGRAM                    20539    
unix  3      [ ]         STREAM     CONNECTED     20421    
unix  3      [ ]         STREAM     CONNECTED     21092    
unix  3      [ ]         STREAM     CONNECTED     18951    
unix  2      [ ]         DGRAM                    23682    
unix  2      [ ]         DGRAM                    20376    
unix  3      [ ]         STREAM     CONNECTED     26990    
unix  3      [ ]         STREAM     CONNECTED     21100    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     18774    
unix  2      [ ]         DGRAM                    23957    
unix  3      [ ]         STREAM     CONNECTED     26995    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     21091    
unix  3      [ ]         STREAM     CONNECTED     22616    
unix  3      [ ]         STREAM     CONNECTED     21096    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     18237    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     25678    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     21101    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     29575    
unix  3      [ ]         STREAM     CONNECTED     21083    
unix  3      [ ]         STREAM     CONNECTED     20213    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     24486    
unix  3      [ ]         STREAM     CONNECTED     20428    
unix  2      [ ]         DGRAM                    21055    
unix  3      [ ]         STREAM     CONNECTED     28819    /run/containerd/containerd.sock
unix  3      [ ]         STREAM     CONNECTED     21098    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     21056    
unix  3      [ ]         STREAM     CONNECTED     18933    
unix  3      [ ]         STREAM     CONNECTED     23569    
unix  3      [ ]         STREAM     CONNECTED     21035    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     21095    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     22801    /run/systemd/journal/stdout
unix  2      [ ]         DGRAM                    21054    
unix  3      [ ]         STREAM     CONNECTED     21093    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     19104    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     28821    
unix  3      [ ]         STREAM     CONNECTED     21034    
unix  3      [ ]         STREAM     CONNECTED     21094    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     28525    /run/containerd/containerd.sock
unix  2      [ ]         DGRAM                    19014    
unix  3      [ ]         STREAM     CONNECTED     20929    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     23753    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     31073    /run/containerd/s/f173b4c37ec27fe764ea6843063c75576d07f7ac21d51986b75d8e816f41033e
unix  3      [ ]         STREAM     CONNECTED     18929    
unix  3      [ ]         STREAM     CONNECTED     24056    
unix  3      [ ]         STREAM     CONNECTED     26698    
unix  3      [ ]         STREAM     CONNECTED     20778    /run/systemd/journal/stdout
unix  3      [ ]         STREAM     CONNECTED     18853    
unix  2      [ ]         DGRAM                    23961    
unix  2      [ ]         DGRAM                    18992    
unix  3      [ ]         STREAM     CONNECTED     20853

top、htop

1
root@raspbian:~# top
1
root@raspbian:~# htop

last

last可用查看用户登录系统的记录，包括用户名、登录的远程名称或者ip地址以及登录时间。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
root@raspbian:~# last
root     pts/0        127.0.0.1        Sun Sep  4 09:43   still logged in
root     pts/0        127.0.0.1        Sun Sep  4 09:16 - 09:36  (00:20)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00   still running
root     pts/0        10.8.3.28        Sat Sep  3 10:07 - 10:07  (00:00)
root     pts/0        127.0.0.1        Sat Sep  3 09:13 - 09:15  (00:01)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00   still running
root     pts/0        10.8.3.28        Fri Sep  2 13:17 - crash (-19237+05:17)
root     pts/1        127.0.0.1        Thu Sep  1 10:42 - 10:51  (00:08)
root     pts/0        10.8.3.28        Thu Sep  1 10:10 - 13:45  (03:35)
root     pts/1        10.71.22.140     Thu Sep  1 08:55 - 09:33  (00:38)
root     pts/1        10.71.22.140     Thu Sep  1 08:40 - 08:54  (00:14)
root     pts/0        10.71.22.140     Thu Sep  1 08:38 - 09:33  (00:55)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00   still running
root     pts/0        10.8.3.28        Wed Aug 31 23:58 - crash (-19235+15:58)
root     pts/1        10.8.3.28        Wed Aug 31 23:13 - crash (-19235+15:13)
root     pts/0        127.0.0.1        Wed Aug 31 23:11 - 23:50  (00:38)
root     pts/0        127.0.0.1        Wed Aug 31 23:06 - 23:11  (00:04)
root     pts/0        127.0.0.1        Wed Aug 31 23:03 - 23:06  (00:02)
root     pts/0        127.0.0.1        Wed Aug 31 23:02 - 23:02  (00:00)
root     pts/0        127.0.0.1        Wed Aug 31 23:00 - 23:02  (00:02)
root     pts/0        127.0.0.1        Wed Aug 31 22:57 - 22:58  (00:01)
root     pts/0        127.0.0.1        Wed Aug 31 22:54 - 22:56  (00:02)
root     pts/0        127.0.0.1        Wed Aug 31 22:31 - 22:52  (00:21)
root     pts/0        10.73.159.18     Wed Aug 31 14:28 - 14:29  (00:00)
root     pts/0        10.73.159.18     Wed Aug 31 14:28 - 14:28  (00:00)
root     pts/0        10.73.159.18     Wed Aug 31 14:19 - 14:19  (00:00)
root     pts/0        10.73.159.18     Wed Aug 31 14:19 - 14:19  (00:00)
root     pts/0        10.73.159.18     Wed Aug 31 14:16 - 14:19  (00:02)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00   still running
root     pts/0        10.73.159.18     Wed Aug 31 14:14 - down   (00:00)
root     pts/0        10.73.159.18     Wed Aug 31 14:13 - 14:14  (00:00)
root     pts/0        10.73.159.18     Wed Aug 31 14:10 - 14:13  (00:02)
root     pts/0        127.0.0.1        Tue Aug 30 22:26 - 14:10  (15:43)
root     pts/0        127.0.0.1        Tue Aug 30 20:46 - 22:26  (01:39)
root     pts/0        127.0.0.1        Tue Aug 30 20:42 - 20:45  (00:02)
root     pts/2        10.67.44.114     Tue Aug 30 20:11 - 20:13  (00:01)
root     pts/2        127.0.0.1        Tue Aug 30 20:09 - 20:10  (00:01)
root     pts/0        127.0.0.1        Tue Aug 30 18:33 - 20:31  (01:58)
root     pts/0        127.0.0.1        Tue Aug 30 17:31 - 18:33  (01:01)
root     pts/0        127.0.0.1        Tue Aug 30 16:49 - 16:58  (00:09)
root     pts/0        127.0.0.1        Tue Aug 30 15:57 - 16:27  (00:30)
root     pts/0        127.0.0.1        Tue Aug 30 14:56 - 15:06  (00:10)
root     pts/0        127.0.0.1        Tue Aug 30 14:48 - 14:51  (00:02)
root     pts/0        127.0.0.1        Tue Aug 30 14:36 - 14:44  (00:08)
root     pts/0        127.0.0.1        Tue Aug 30 14:21 - 14:24  (00:02)
root     pts/0        127.0.0.1        Tue Aug 30 13:34 - 14:20  (00:45)
root     pts/0        127.0.0.1        Tue Aug 30 13:13 - 13:14  (00:00)
root     pts/0        127.0.0.1        Tue Aug 30 12:43 - 13:13  (00:29)
root     pts/0        127.0.0.1        Tue Aug 30 12:31 - 12:39  (00:08)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00 - 14:14 (19235+06:14)
root     pts/1        127.0.0.1        Tue Aug 30 12:12 - down   (00:17)
root     pts/1        127.0.0.1        Tue Aug 30 12:12 - 12:12  (00:00)
root     pts/0        127.0.0.1        Tue Aug 30 12:10 - down   (00:19)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00 - 12:30 (19234+04:30)
root     pts/0        127.0.0.1        Mon Aug 29 08:57 - 10:01  (01:04)
root     pts/0        127.0.0.1        Mon Aug 29 08:49 - 08:57  (00:08)
root     pts/0        127.0.0.1        Mon Aug 29 08:16 - 08:17  (00:01)
root     pts/0        127.0.0.1        Mon Aug 29 08:16 - 08:16  (00:00)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00 - 12:30 (19234+04:30)
root     pts/0        10.8.3.28        Sun Aug 28 21:53 - 22:10  (00:17)
root     pts/0        10.8.3.28        Sun Aug 28 20:17 - 21:44  (01:27)
root     pts/0        10.8.3.28        Sun Aug 28 20:12 - 20:12  (00:00)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00 - 12:30 (19234+04:30)
root     pts/0        192.168.1.100    Sun Aug 28 13:27 - crash (-19232+05:27)
pi       pts/0        192.168.1.100    Sun Aug 28 01:10 - 01:15  (00:04)
root     pts/1        127.0.0.1        Sun Aug 28 00:45 - 00:45  (00:00)
root     pts/1        127.0.0.1        Sun Aug 28 00:45 - 00:45  (00:00)
pi       pts/0        192.168.1.100    Sun Aug 28 00:30 - 01:09  (00:38)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00 - 12:30 (19234+04:30)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00 - 18:13 (17941+10:13)
reboot   system boot  5.10.78-Release- Thu Jan  1 08:00 - 18:12 (17941+10:12)

wtmp begins Thu Jan  1 08:00:03 1970

ulimit

Too many open files是Linux系统中常见的错误，从字面意思上看就是说程序打开的文件数过多，不过这里的files不单是文件的意思，也包括打开的通讯链接(比如socket)，正在监听的端口等等，所以有时候也可以叫做句柄(handle)，这个错误通常也可以叫做句柄数超出系统限制。引起的原因就是进程在某个时刻打开了超过系统限制的文件数量以及通讯链接数。

通过命令ulimit -a可以查看当前系统设置的最大句柄数是多少

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 31767
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) 31767
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

可以看到，open files的配置是1024，可以通过如下命令将open files增加

1
ulimit -n 65535

这种修改方式可以临时把文件打开数量增加到65535，但是系统重启后这个配置会失效。

还有一种方式是修改系统的配置文件，以Ubuntu为例，配置文件默认在

1
/etc/security/limits.conf

在这个配置文件中增加

1
2
* soft nofile 65535
* hard nofile 65535