我有一个包含以下行的文本文件：
[...]
GFX Clocks and Power:
800 MHz (MCLK)
26 MHz (SCLK)
[...]
我想提取800 MHz它的一部分（值不是恒定的），所以我想删除\t并(MCLK)使用sed.
这是我现在的命令：
$ cat ~/test.txt | grep "(MCLK)" | xargs -0 sed -i -e $'s/\t//g' -e 's/\(MCLK\)//g'
运行时，它返回：
sed: can't read 800 MHz (MCLK)
: No such file or directory
这似乎不是换行错误，应该解决有关\t成为非标准字符的问题sed（参见简单的 sed 替换选项卡神秘地失败）。
可能是什么问题？
apt update由于多个签名的公钥不可用，更新存储库失败。
$ sudo apt update
Get:1 http://security.debian.org/debian-security stretch/updates InRelease [94.3 kB]
Ign:2 http://deb.debian.org/debian stretch InRelease
Hit:3 http://deb.debian.org/debian stretch Release
Ign:4 http://ftp.fr.debian.org/debian stretch InRelease
Ign:6 http://ftp.fr.debian.org/debian jessie InRelease
Hit:7 https://fr.archive.ubuntu.com/ubuntu bionic InRelease
Hit:8 http://ftp.fr.debian.org/debian stretch Release
Get:5 http://ftp.fr.debian.org/debian stretch-updates InRelease [91.0 kB]
Hit:9 https://riot.im/packages/debian stretch InRelease
Hit:10 http://ftp.fr.debian.org/debian jessie Release
Err:1 http://security.debian.org/debian-security stretch/updates InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9D6D8F6BC857C906 NO_PUBKEY 8B48AD6246925553
Get:11 https://mega.nz/linux/MEGAsync/Debian_9.0 ./ InRelease [1,480 B]
Ign:12 http://download.opensuse.org/repositories/home:/strycore/Debian_9.0 ./ InRelease
Hit:13 http://download.opensuse.org/repositories/home:/strycore/Debian_9.0 ./ Release
Err:14 http://deb.debian.org/debian stretch Release.gpg
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010 NO_PUBKEY EF0F382A1A7B6500
Get:15 https://content.runescape.com/downloads/ubuntu trusty InRelease [2,236 B]
Err:16 http://ftp.fr.debian.org/debian stretch Release.gpg
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010 NO_PUBKEY EF0F382A1A7B6500
Err:9 https://riot.im/packages/debian stretch InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E019645248E8F4A1
Err:5 http://ftp.fr.debian.org/debian stretch-updates InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010
Err:17 http://ftp.fr.debian.org/debian jessie Release.gpg
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010 NO_PUBKEY CBF8D6FD518E17E1
Err:11 https://mega.nz/linux/MEGAsync/Debian_9.0 ./ InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4B4E7A9523ACD201
Err:18 http://download.opensuse.org/repositories/home:/strycore/Debian_9.0 ./ Release.gpg
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 2F7F0DA5FD5B64B9
Err:15 https://content.runescape.com/downloads/ubuntu trusty InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7373B12CE03BEB4B
Reading package lists... Done
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://security.debian.org/debian-security stretch/updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9D6D8F6BC857C906 NO_PUBKEY 8B48AD6246925553
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://deb.debian.org/debian stretch Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010 NO_PUBKEY EF0F382A1A7B6500
W: Skipping acquire of configured file 'xenial/binary-amd64/Packages' as repository 'https://fr.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'xenial' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'xenial/binary-i386/Packages' as repository 'https://fr.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'xenial' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'xenial/i18n/Translation-en_US' as repository 'https://fr.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'xenial' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'xenial/i18n/Translation-en' as repository 'https://fr.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'xenial' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'xenial/dep11/Components-amd64.yml' as repository 'https://fr.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'xenial' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'xenial/dep11/icons-64x64.tar' as repository 'https://fr.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'xenial' (component misspelt in sources.list?)
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://ftp.fr.debian.org/debian stretch Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010 NO_PUBKEY EF0F382A1A7B6500
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://riot.im/packages/debian stretch InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E019645248E8F4A1
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://ftp.fr.debian.org/debian stretch-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://ftp.fr.debian.org/debian jessie Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010 NO_PUBKEY CBF8D6FD518E17E1
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://mega.nz/linux/MEGAsync/Debian_9.0 ./ InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4B4E7A9523ACD201
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://download.opensuse.org/repositories/home:/strycore/Debian_9.0 ./ Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 2F7F0DA5FD5B64B9
W: GPG error: https://content.runescape.com/downloads/ubuntu trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7373B12CE03BEB4B
E: The repository 'https://content.runescape.com/downloads/ubuntu trusty InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
我试图在没有的情况下更新密钥keyring.debian.org
$ gpg --recv-keys 9D6D8F6BC857C906
gpg: key 9D6D8F6BC857C906: 12 signatures not checked due to missing keys
gpg: key 9D6D8F6BC857C906: "Debian Security Archive Automatic Signing Key (8/jessie) <[email protected]>" not changed
gpg: Total number processed: 1
gpg: unchanged: 1
与
$ gpg --keyserver keyring.debian.org --recv-keys 9D6D8F6BC857C906
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
ca-certificates与 version20180409以及debian-keyringversion都是最新的2018.03.24。
我也/etc/apt/trusted.gpg根据https://serverfault.com/q/851724删除了。
@斯蒂芬基特的要求：
$ ls -la /etc/apt/trusted.gpg.d
total 28
drwxr-xr-x 2 root root 4096 Jan 2 10:42 .
drwxr-xr-x 6 root root 4096 Jan 2 11:06 ..
-rw-r--r-- 1 root root 10345 Jan 2 10:42 ubuntu-keyring-2012-archive.gpg
-rw-r--r-- 1 root root 2796 Feb 6 2018 ubuntu-keyring-2012-archive.gpg~
-rw-r--r-- 1 root root 2794 Feb 6 2018 ubuntu-keyring-2012-cdimage.gpg
$ apt policy debian-archive-keyring
debian-archive-keyring:
Installed: 2017.7ubuntu1
Candidate: 2017.7ubuntu1
Version table:
*** 2017.7ubuntu1 500
500 https://fr.archive.ubuntu.com/ubuntu bionic/universe amd64 Packages
500 https://fr.archive.ubuntu.com/ubuntu bionic/universe i386 Packages
100 /var/lib/dpkg/status
2017.5 500
500 http://ftp.fr.debian.org/debian stretch/main amd64 Packages
500 http://ftp.fr.debian.org/debian stretch/main i386 Packages
500 http://deb.debian.org/debian stretch/main amd64 Packages
500 http://deb.debian.org/debian stretch/main i386 Packages
2017.5~deb8u1 500
500 http://ftp.fr.debian.org/debian jessie/main amd64 Packages
500 http://ftp.fr.debian.org/debian jessie/main i386 Packages
如何解决导入正确密钥的问题？
我最近更新了我的 Linux 4.9.0-8 debian 6.3.0。但是，当我重新启动机器时，标题中出现了消息。阻止我访问图形终端。我无法访问我的文件，这非常严重。所有图标和图像都无法加载。我无法打开任何窗口，但 GNOME 似乎可以正常工作。
我尝试通过恢复模式更新 GRUB，但除此之外，我没有太多想法。
我有一些视频文件source/要编码，我希望将输出保存在本地目录中，因此source/在文件名中删除。
我通过在鱼壳中使用以下命令来完成此操作：
$ for file in source/*.mkv
ffmpeg -i "$file" -c:v copy -c:a copy (echo "$file" | sed -e "s/source\///")
end
虽然，我发现管道的输出echo有点sed初级，但是否有一个函数只处理局部变量的字符串？像 ased但仅用于局部变量或文件名。
我在一台装有 GRUB 的机器上双启动 Windows 和 Fedora。每当我更新 Fedora 或其 Linux 内核时，它都会生成一个新的磁盘映像，/boot从而在加载 GRUB 时创建另一个引导选项。但是，每当我更新发行版或其内核时，另一台机器上的 Arch Linux 都没有变化/boot。
如果我对它的工作原理有错误的理解，请原谅我；当 Linux 内核或发行版得到更新并且新的引导映像得到更新时，这是否意味着以前版本的映像基本上已被弃用，它们不应该被删除（因此被更新的对应版本替换）吗？
为什么会生成一个新的和不同的图像/boot？简单地删除以前的版本是否安全？