System (系统) – Eternal Center

January 20, 2025January 20, 2025

[步骤] Linux su 命令使用的限制（只让某些用户使用 su 命令）（openSUSE & SLES 版）

步骤一：创建可以使用 su 命令的组

# gourpadd whocansu

（补充：这里以创建组 whocansu 为例）

步骤二：将需要使用 su 命令的用户添加到可以使用 su 命令的组里

# usermod -a -G whocansu zhumingyu

或者：

# usermod -aG whocansu zhumingyu

（补充：这里以将用户 zhumingyu 添加到 whocansu 组为例）

步骤三：设置着只让某个组队用户可以使用 su 命令

# vim /etc/pam.d/su

添加以下内容：

#%PAM-1.0
auth required pam_wheel.so use_uid group=whocansu
......

（补充：这里以只允许组 whocansu 可以使用 su 命令为例）

（注意：此时如果用户有 sudo su 权限的话，那么依旧可以通过 sudo su 命令切换到 root）

December 13, 2024December 13, 2024

[STEP] Limitation of the amount of the file which can be opened by Linux program

Step One: In system level, set the limitation of the amount of the files which can be opened by the user who running the Linux Program

# vi /etc/security/limites.conf

Add these lines:

......
rmt  -       nofile  1024
rmt  -       nproc   1024

(Add: Setting the rmt user can open 8192 files and 8192 processes in this Linux as an example here)

Step Two: In program level, check the setting of the amount of the files which can be opened by Linux program

# /bin/systemctl show 'rmt-server-mirror.service' | sort
......
LimitNOFILE=524288
......

(Add: The amount of opening the file by program rmt-server-mirror.service is limited at 8096 as an example here)

December 5, 2024December 5, 2024

[排错] Linux 解决使用 scp 命令时报错 scp: dest open “……”: Failure

报错代码：

> scp test.txt 192.168.0.1:
scp: dest open "./test.txt": Failure
scp: failed to upload file test.txt to .

（补充：这里以将 test.txt 文件传到 IP 地址 192.168.0.1 同名用户的家目录然后报错为例）

分析：

可能是目标目录的空间不够了

解决方法：

在目标目录上释放一些空间

November 29, 2024November 29, 2024

[内容] 硬盘的模式

Write-through （直写模式）

数据同时写如 Cache （缓存）和硬盘。
优点是：不会出现突然断电掉数据的情况
缺点是：但是写入速度较慢

Write-back （回写模式）

数据先写入 Cache （缓存），再从 Cache （缓存）写入硬盘。
优点是：写入速度较快
缺点是：突然断电存储在 Cache （缓存）里的数据无法找回

November 27, 2024

[内容] Linux 网卡状态的显示

方法一：ip 命令

# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:1c:42:c9:3c:81 brd ff:ff:ff:ff:ff:ff
    inet 10.10.10.129/24 brd 10.10.10.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fdb2:2c26:f4e4:0:55da:1265:541f:8007/64 scope global temporary dynamic 
       valid_lft 563315sec preferred_lft 44695sec
    inet6 fdb2:2c26:f4e4:0:21c:42ff:fec9:3c81/64 scope global dynamic mngtmpaddr 
       valid_lft 2591846sec preferred_lft 604646sec
    inet6 fe80::21c:42ff:fec9:3c81/64 scope link 
       valid_lft forever preferred_lft forever

或者：

# ip a s
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:1c:42:c9:3c:81 brd ff:ff:ff:ff:ff:ff
    inet 10.10.10.129/24 brd 10.10.10.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fdb2:2c26:f4e4:0:55da:1265:541f:8007/64 scope global temporary dynamic 
       valid_lft 563315sec preferred_lft 44695sec
    inet6 fdb2:2c26:f4e4:0:21c:42ff:fec9:3c81/64 scope global dynamic mngtmpaddr 
       valid_lft 2591846sec preferred_lft 604646sec
    inet6 fe80::21c:42ff:fec9:3c81/64 scope link 
       valid_lft forever preferred_lft forever

或者：

# ip address show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:1c:42:c9:3c:81 brd ff:ff:ff:ff:ff:ff
    inet 10.10.10.129/24 brd 10.10.10.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fdb2:2c26:f4e4:0:55da:1265:541f:8007/64 scope global temporary dynamic 
       valid_lft 563315sec preferred_lft 44695sec
    inet6 fdb2:2c26:f4e4:0:21c:42ff:fec9:3c81/64 scope global dynamic mngtmpaddr 
       valid_lft 2591846sec preferred_lft 604646sec
    inet6 fe80::21c:42ff:fec9:3c81/64 scope link 
       valid_lft forever preferred_lft forever

方法二：ifconfig 命令

# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.10.10.129  netmask 255.255.255.0  broadcast 10.10.10.255
        inet6 fdb2:2c26:f4e4:0:21c:42ff:fec9:3c81  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::21c:42ff:fec9:3c81  prefixlen 64  scopeid 0x20<link>
        inet6 fdb2:2c26:f4e4:0:55da:1265:541f:8007  prefixlen 64  scopeid 0x0<global>
        ether 00:1c:42:c9:3c:81  txqueuelen 1000  (Ethernet)
        RX packets 698666  bytes 485434755 (462.9 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 372557  bytes 699406543 (667.0 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 73792  bytes 394285172 (376.0 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 73792  bytes 394285172 (376.0 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

方法三：iwconfig 命令

# iwconfig 
lo        no wireless extensions.

eth0      no wireless extensions.