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mazda's questions

Martin Hope
mazda
Asked: 2025-03-31 03:05:26 +0800 CST
  • 6

当我想重定向 ffprobe 命令的 stdout 时，我大吃一惊：通常的stdout > (file)不起作用。经过几次网络搜索，我找到了答案：我必须使用stdout > (file) 2>&1，这样就可以了：https://stackoverflow.com/questions/29680391/ffmpeg-command-line-write-output-to-a-text-file。

什么可以解释为什么将输出重定向到文件的常用方法对我不起作用：我使用的 ffprobe 版本？ shell？还是其他什么？

~$ ffprobe --version
ffprobe version 5.1.6-0+deb12u1 Copyright (c) 2007-2024 the FFmpeg developers
  built with gcc 12 (Debian 12.2.0-14)

或者由程序员来选择重定向的行为方式，如下面这个评论所解释的：

 @Apostolos it's up to the programmer, you may want to keep normal
 output separate from error output.
debian
Martin Hope
mazda
Asked: 2025-03-04 18:54:50 +0800 CST
  • 5

我通过查询网络解决了一个问题，但不幸的是，没有解释为什么我找到的命令有效。

我需要使用 cron/anacron 运行一个脚本并在终端屏幕上显示结果，为了在此脚本的最后一行执行此操作，我首先尝试了此命令：

xterm -hold -e 'cd /home/<user>/ && cat inode2 ; bash'

只有我自己运行脚本时它才有效。我将其替换为：

DISPLAY=:0 xterm -hold -e 'cd /home/mmas/ && cat inode2 ; bash'

据我所知，DISPLAY=:0 表示“选择当前显示屏”。结果如下：我的笔记本电脑的活动窗口中出现了一个小终端屏幕，显示脚本结果。在我的 ~/.bashrc 和 /root/.bashrc 文件中，已经有一个“export DISPLAY=:0.0”。显然，cron 对此并不知情。

我的问题是：

  1. 在修改后的命令中，DISPLAY=:0 真的意味着“显示当前活动窗口的屏幕”还是其他什么？
  2. 为什么我必须在命令开始时指定它？
linux
Martin Hope
mazda
Asked: 2025-02-25 00:53:51 +0800 CST
  • 5
~$ echo $(date +%a%d\ %X)
lun.24 17:40:28

~$ inode-1
thunar.desktop
lun.24% +17:40:40

~$ cat inode-1 
#/bin/bash
# inode_check

xdg-mime query default inode/directory >> /home/<user>/f1;
echo $(date +%a%d%\ +%X)  >> /home/<user>/f1;
cat f1

您如何解释脚本输出中出现 lun.24% 的原因？删除 % 字符的正确语法是什么？

linux
Martin Hope
mazda
Asked: 2025-01-03 00:04:27 +0800 CST
  • 6

由于联发科 MT7902 Wi-Fi 卡没有 Linux 驱动程序，我目前使用 USB 适配器（TP-Link AC600 无线 Archer T2U Nano），该适配器与该rtl8821au模块配合良好。我想使用联发科 Wi-Fi 卡找回这个 USB 连接器。

为了使联发科 MT7902 Wi-Fi 卡工作，我使用了此 GitHub 页面上的驱动程序，但该卡仍然无法工作。

~$ uname -a
Linux asus 6.1.0-28-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.119-1 (2024-11-22) x86_64 GNU/Linux

~$ lspci -nnkd ::280
0000:02:00.0 Network controller [0280]: MEDIATEK Corp. Device [14c3:7902]
    DeviceName: WLAN
    Subsystem: AzureWave Device [1a3b:5520]

~# dkms status
ndiswrapper/1.60: added
rtl8821au/5.12.5.2, 6.1.0-27-amd64, x86_64: installed
rtl8821au/5.12.5.2, 6.1.0-28-amd64, x86_64: installed

~# modinfo ndiswrapper
modinfo: ERROR: Module ndiswrapper not found.

~# ndiswrapper -l
mtkwl6ex : driver installed
    device (14C3:7902) present

~$ nmcli connection 
NAME                UUID                                  TYPE      DEVICE          
Livebox-xxxxxxxx    90bdcfd0-3bdf-4e83-bc3e-f31e5b4c18fd  wifi      wlxe4fac451e278 
lo                  f909b88d-0257-4174-ad16-37295c420ebd  loopback  lo              
Livebox-xxxxxx      1c2b204c-63e4-4b79-aa65-cbf69e038b29  wifi      --              
Wired connection 1  49f2d538-509d-4f64-9ee1-b568dd950ec6  ethernet  --

~# en rfkill
ID TYPE      DEVICE              SOFT      HARD
 1 wlan      asus-wlan      unblocked unblocked
 2 bluetooth asus-bluetooth unblocked unblocked
 3 bluetooth hci0           unblocked unblocked
 4 wlan      phy1           unblocked unblocked

我还可以检查什么来找出为什么我没有 MT7902 卡的 Wi-Fi 连接？为什么ndiswrapper找不到？

~# ndiswrapper -v
modinfo: ERROR: Module ndiswrapper not found.
module version is too old!
utils version: '1.9', utils version needed by module: '0'
module details:
modinfo: ERROR: Module ndiswrapper not found.
linux
Martin Hope
mazda
Asked: 2024-08-12 00:47:52 +0800 CST
  • 5

要显示我的显卡的特性，我可以使用以下两个命令之一：

 ~$ lspci -nn | grep VGA
 ~$ lspci -nnkd ::300

我理解前者，但由于部分原因，我不理解后者::300。

我认为它一定是某种显卡标识符，但我不知道在哪里可以找到有关此代码的信息。如果它是代码，我不知道。

我的问题是：我在哪里可以找到有关 的含义的信息::300？或者更一般地讲，有关 任何 的信息::xxx？

linux
Martin Hope
mazda
Asked: 2024-04-25 19:53:05 +0800 CST
  • 5

为此，我似乎有两个选择：

  1. 将（用户）添加到 sudo 组：
# usermod -aG sudo <user>
  1. 将（用户）添加到 /etc/sudoers
# visudo /etc/sudoers
.........
<user> ALL=(ALL:ALL) ALL
....

Are these two methods equivalent, or is one better than the other, and why?
linux
Martin Hope
mazda
Asked: 2024-03-17 16:21:42 +0800 CST
  • 5

尝试了解du命令的基础知识对我来说并不那么简单。例如，有一个-h选项被定义为以“人类可读格式”打印。问题是此选项更改了显示值：

~$ du --apparent-size -sh Documents/
376M    Documents/
~$ du --apparent-size -s Documents/
384767  Documents/

通常 384767 应四舍五入为 385M。那么 376M 和 385M 哪个是正确的值呢？

更糟 ：

~$ du -bsh Documents/
    376M    Documents/
~$ du -bs Documents/
    394001294   Documents/
linux
Martin Hope
mazda
Asked: 2023-08-19 15:20:38 +0800 CST
  • 6

我有两台笔记本电脑 [L1、L2] 连接到同一个盒子，都使用 Debian 11：

  • L1：通过以太网连接，无线网卡开启
  • L2：仅通过 WiFi 连接

使用此配置，我无法使用 SSH 将 L1 [客户端] 连接到 L2 [服务器]，如果我想使用 SSH，我必须断开 L1 的以太网电缆或关闭 L1 的 WiFi，并且想了解原因:

  • 客户： 
    ~$ ip -brief addr

  lo               UNKNOWN        127.0.0.1/8 ::1/128
  enp1s0f1         UP             192.168.1.24/24 fe80::id1
  wlp2s0           UP             192.168.1.24/24 fe80::id2

    ~$ ssh -vvv xxx@192.168.1.21

  OpenSSH_8.4p1 Debian-5+deb11u1, OpenSSL 1.1.1n  15 Mar 2022

  debug1: Reading configuration data /etc/ssh/ssh_config
  debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
  debug1: /etc/ssh/ssh_config line 21: Applying options for *

  debug2: resolve_canonicalize: hostname 192.168.1.21 is address
  debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/home/xxx/.ssh/known_hosts'
  debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/home/xxx/.ssh/known_hosts2'
  debug2: ssh_connect_direct

  debug1: Connecting to 192.168.1.21 [192.168.1.21] port 22.
  debug1: connect to address 192.168.1.21 port 22: No route to host

  ssh: connect to host 192.168.1.21 port 22: No route to host

  • 服务器： 
    ~# /usr/sbin/sshd -d

  debug1: sshd version OpenSSH_9.2, OpenSSL 3.0.9 30 May 2023
  debug1: private host key #0: ssh-rsa
  debug1: private host key #1: ecdsa-sha2-nistp256
  debug1: private host key #2: ssh-ed25519

  debug1: rexec_argv[0]='/usr/sbin/sshd'
  debug1: rexec_argv[1]='-d'
  debug1: Set /proc/self/oom_score_adj from 0 to -1000

  debug1: Bind to port 22 on 0.0.0.0.
  Server listening on 0.0.0.0 port 22.
  debug1: Bind to port 22 on ::.
  Server listening on :: port 22.

  debug1: Server will not fork when running in debugging mode.
  debug1: rexec start in 5 out 5 newsock 5 pipe -1 sock 8

  debug1: sshd version OpenSSH_9.2, OpenSSL 3.0.9 30 May 2023
  debug1: private host key #0: ssh-rsa SHA256:
  debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:
  debug1: private host key #2: ssh-ed25519 SHA256:
  debug1: inetd sockets after dupping: 3, 3

  Connection from 192.168.1.24 port 36154 on 192.168.1.21 port 22 rdomain ""

  debug1: Local version string SSH-2.0-OpenSSH_9.2p1 Debian-2
  debug1: Remote protocol version 2.0, remote software version OpenSSH_8.4p1 Debian-5+deb11u1
  debug1: compat_banner: match: OpenSSH_8.4p1 Debian-5+deb11u1 pat OpenSSH* compat 0x04000000
  debug1: permanently_set_uid: 115/65534 [preauth]
  debug1: list_hostkey_types: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
  debug1: SSH2_MSG_KEXINIT sent [preauth]
  debug1: SSH2_MSG_KEXINIT received [preauth]
  debug1: kex: algorithm: curve25519-sha256 [preauth]
  debug1: kex: host key algorithm: ecdsa-sha2-nistp256 [preauth]
  debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none [preauth]
  debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none [preauth]
  debug1: expecting SSH2_MSG_KEX_ECDH_INIT [preauth]
  debug1: SSH2_MSG_KEX_ECDH_INIT received [preauth]
  debug1: rekey out after 134217728 blocks [preauth]
  debug1: SSH2_MSG_NEWKEYS sent [preauth]
  debug1: Sending SSH2_MSG_EXT_INFO [preauth]
  debug1: expecting SSH2_MSG_NEWKEYS [preauth]
  debug1: SSH2_MSG_NEWKEYS received [preauth]
  debug1: rekey in after 134217728 blocks [preauth]
  debug1: KEX done [preauth]
  debug1: userauth-request for user xxx  service ssh-connection method none [preauth]
  debug1: attempt 0 failures 0 [preauth]
  debug1: PAM: initializing for "xxx"
  debug1: PAM: setting PAM_RHOST to "192.168.1.24"
  debug1: PAM: setting PAM_TTY to "ssh"
  debug1: userauth_send_banner: sent [preauth]
  debug1: userauth-request for user xxx service ssh-connection method publickey [preauth]

  debug1: attempt 1 failures 0 [preauth]
  debug1: userauth_pubkey: publickey test pkalg rsa-sha2-512 pkblob RSA SHA256:[preauth]
  debug1: temporarily_use_uid: 1000/1000 (e=0/0)
  debug1: trying public key file /home/mi/.ssh/authorized_keys
  debug1: fd 4 clearing O_NONBLOCK
  debug1: /home/xxx/.ssh/authorized_keys:1: matching key found: RSA SHA256:
  debug1: /home/xxx/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding

  Accepted key RSA SHA256: found at /home/xxx/.ssh/authorized_keys:1
  debug1: restore_uid: 0/0

  Postponed publickey for xxx from 192.168.1.24 port 36154 ssh2 [preauth]

  debug1: userauth-request for user xxx service ssh-connection method publickey [preauth]
  debug1: attempt 2 failures 0 [preauth]
  debug1: temporarily_use_uid: 1000/1000 (e=0/0)
  debug1: trying public key file /home/xxx/.ssh/authorized_keys
  debug1: fd 4 clearing O_NONBLOCK
  debug1: /home/xxx/.ssh/authorized_keys:1: matching key found: RSA SHA256:
  debug1: /home/xxx/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding

  Accepted key RSA SHA256: found at /home/xxx/.ssh/authorized_keys:1

  debug1: restore_uid: 0/0
  debug1: auth_activate_options: setting new authentication options
  debug1: do_pam_account: called

  Accepted publickey for xxx from 192.168.1.24 port 36154 ssh2: RSA SHA256:

  debug1: monitor_child_preauth: user xxx authenticated by privileged process
  debug1: auth_activate_options: setting new authentication options [preauth]
  debug1: monitor_read_log: child log fd closed
  debug1: PAM: establishing credentials

  User child is on pid 2553

  debug1: SELinux support disabled
  debug1: PAM: establishing credentials
  debug1: permanently_set_uid: 1000/1000
  debug1: rekey in after 134217728 blocks
  debug1: rekey out after 134217728 blocks
  debug1: ssh_packet_set_postauth: called
  debug1: active: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
  debug1: Entering interactive session for SSH2.
  debug1: server_init_dispatch
  debug1: server_input_channel_open: ctype session rchan 0 win 1048576 max 16384
  debug1: input_session_request
  debug1: channel 0: new session [server-session] (inactive timeout: 0)
  debug1: session_new: session 0
  debug1: session_open: channel 0
  debug1: session_open: session 0: link with channel 0
  debug1: server_input_channel_open: confirm session
  debug1: server_input_global_request: rtype no-more-sessions@openssh.com want_reply 0
  debug1: server_input_channel_req: channel 0 request pty-req reply 1
  debug1: session_by_channel: session 0 channel 0
  debug1: session_input_channel_req: session 0 req pty-req
  debug1: Allocating pty.
  debug1: session_new: session 0
  debug1: SELinux support disabled
  debug1: session_pty_req: session 0 alloc /dev/pts/1
  debug1: server_input_channel_req: channel 0 request env reply 0
  debug1: session_by_channel: session 0 channel 0
  debug1: session_input_channel_req: session 0 req env
  debug1: server_input_channel_req: channel 0 request shell reply 1
  debug1: session_by_channel: session 0 channel 0
  debug1: session_input_channel_req: session 0 req shell

  Starting session: shell on pts/1 for xxx from 192.168.1.24 port 36154 id 0
linux