请帮助我理解其中的逻辑 - 来自 whereis man：
OPTIONS
-b
Search for binaries.
但是当我使用它时，它会返回目录的路径：
kl@debian:~$ whereis -b postfix
postfix: /usr/sbin/postfix /usr/lib/postfix /etc/postfix
kl@debian:~$ whereis --version
whereis from util-linux 2.38.1
kl@debian:~$ file /usr/lib/postfix
/usr/lib/postfix: directory
kl@debian:~$ file /etc/postfix
/etc/postfix: directory
kl@debian:~$
如何检查 Linux 系统上当前工作目录中有多少可用空间？
我有一个filesize文件，其中包含1073741824所需的磁盘空间量（以字节为单位）。
我需要在脚本中检查文件夹中是否有文件内容大小 * 1.25 字节的空闲空间。该怎么做？
pwd可以打印当前文件夹的路径，但是如何将其与之结合起来df？
我无法使用命令捕获br0（Linux 桥接器）接口上的单播流量。但是，广播流量按预期被捕获。有趣的是，如果我打开另一个终端并运行以同时捕获 br0 接口上的流量，则可以捕获单播流量。tcpdump -nni any -vvvtcpdump -nni br0 -vvv
tcpdump我注意到版本4.9.3 （libpcap 版本 1.8.1）中存在此行为，其中tcpdump -nni any -vvv命令不会捕获 br0 单播流量。但是，使用tcpdump版本4.99.5（带有 TPACKET_V3 的 libpcap 版本 1.10.5）可以正常工作并捕获 br0 上的单播流量。
我知道 br0 获取流入 Linux 桥接设备的所有流量，另请参阅Linux 桥接器的解剖。
如果传入帧的目标 MAC 地址是多地址或广播地址，桥接设备设置为接收所有流量，或者地址与本地接口之一匹配，则还会通过调用 br_pass_frame_ up 函数在本地网络堆栈中向上传递帧的克隆。该函数更新桥接设备统计信息，并通过调用独立于设备的 netif_receive_skb 函数将传入的帧传递到网络堆栈
我怀疑我看到的可能与版本tcpdump或其参数有关，但我无法确认这一点。你能帮忙解释一下这种行为的原因吗？
sudo rm -r我意外地在 RAID 1 安装点上运行。我立即意识到了自己的错误，惊慌失措，并点击CTRL+C取消。一些损害已经造成。lost+found目录和一些数据消失了，但大部分数据仍然存在。我可以恢复丢失的数据，但我担心 RAID 的完整性和目录lost+found。所以我有两个问题：
我的 RAID 还好吗？假设我删除了整个 RAID 安装点。这只会删除数据和安装点，但 RAID 本身仍然完好无损。因此可以重新安装，然后我可以从备份中恢复数据。对吗？
我需要担心lost+found目录吗？如果我理解正确的话，lost+found目录仅包含在磁盘上找到的未链接文件的名称。因此删除它应该不是问题，因为不受欢迎的文件本身不会被删除，它们会再次被找到并以新名称放置在中lost+found。对吗？
以下是 RAID 的一些信息输出：
user@host:~ $ cat /proc/mdstat
Personalities : [raid1] [linear] [raid0] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdb1[1] sda1[0]
5860385344 blocks super 1.2 [2/2] [UU]
bitmap: 0/44 pages [0KB], 65536KB chunk
unused devices: <none>
user@host:~ $ sudo mdadm --detail /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Fri May 31 11:25:15 2024
Raid Level : raid1
Array Size : 5860385344 (5.46 TiB 6.00 TB)
Used Dev Size : 5860385344 (5.46 TiB 6.00 TB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Fri Sep 27 15:14:40 2024
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Consistency Policy : bitmap
Name : host:0 (local to host host)
UUID : ...
Events : 87057
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 17 1 active sync /dev/sdb1
user@host:~ $ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sda 8:0 0 5.5T 0 disk
└─sda1 8:1 0 5.5T 0 part
└─md0 9:0 0 5.5T 0 raid1 /mount/raid1
sdb 8:16 0 5.5T 0 disk
└─sdb1 8:17 0 5.5T 0 part
└─md0 9:0 0 5.5T 0 raid1 /mount/raid1
...
总之，作为一个外行，我觉得一切都很好，但我还是想在这里问一下，以确保万无一失。任何帮助或参考点都将不胜感激！
我有两个应用程序用于传输数据：
应用程序1 | 应用程序2
基本上，应用程序 1 会生成一个日志，其中包含应用程序 2 处理的事件。问题是我经常更新应用程序 2。这意味着，我需要停止这些更新，更新二进制文件，然后重新启动它。在那段短暂的时间内，应用程序 1 可能会丢失数据。
我读到过有关使用命名管道的文章mkfifo，并认为这可能是一个理想的解决方案。保持应用程序 1 运行，并让它写入文件支持的命名管道，这样当应用程序更新时不会丢失数据，并且一旦应用程序 2 启动，它就会获取数据。
测试cat模拟读取器/写入器是否有效，直到不再有读取器。这是意料之外的。
另一种方法是使用实际文件，但存在问题：
我控制着阅读器，目前的行为是它会自动重启，但我无法控制写入器。我只能将其输出通过管道传输到其他地方。
解决方案https://unix.stackexchange.com/a/784153/585995有效！
mkfifo /tmp/mypipe
writerapp 1<>/tmp/mypipe
当我重新启动阅读器时，编写器继续运行：
readerapp </tmp/mypipe
顺便说一句，你可以自己使用以下方法测试一下cat
根据这个输出，/var/log/Xorg.0.log当我想开始X写的时候
启动
然后输出显示。
X.Org X Server 1.21.1.11
X Protocol Version 11, Revision 0
[ 1198.198] Current Operating System: Linux stm32-os 6.1.82 #1 PREEMPT Tue Sep 10 21:04:28 CEST 2024 armv7l
[ 1198.199] Kernel command line: root=PARTUUID=e91c4e10-16e6-4c0e-bd0e-77becf4a3582 rootwait rw console=ttySTM0,115200
[ 1198.199] xorg-server 2:21.1.12-1ubuntu1 (For technical support please see http://www.ubuntu.com/support)
[ 1198.199] Current version of pixman: 0.42.2
[ 1198.199] Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
[ 1198.199] Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[ 1198.200] (==) Log file: "/var/log/Xorg.0.log", Time: Fri Apr 19 14:44:17 2024
[ 1198.202] (==) Using config directory: "/etc/X11/xorg.conf.d"
[ 1198.202] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[ 1198.204] (==) No Layout section. Using the first Screen section.
[ 1198.205] (**) |-->Screen "DefaultScreen" (0)
[ 1198.205] (**) | |-->Monitor "<default monitor>"
[ 1198.206] (**) | |-->Device "Mali FBDEV"
[ 1198.206] (==) No monitor specified for screen "DefaultScreen".
Using a default monitor configuration.
[ 1198.206] (**) Allowing byte-swapped clients
[ 1198.206] (==) Automatically adding devices
[ 1198.206] (==) Automatically enabling devices
[ 1198.207] (==) Automatically adding GPU devices
[ 1198.207] (==) Automatically binding GPU devices
[ 1198.207] (==) Max clients allowed: 256, resource mask: 0x1fffff
[ 1198.207] (WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist.
[ 1198.207] Entry deleted from font path.
[ 1198.207] (WW) The directory "/usr/share/fonts/X11/100dpi/" does not exist.
[ 1198.207] Entry deleted from font path.
[ 1198.207] (WW) The directory "/usr/share/fonts/X11/75dpi/" does not exist.
[ 1198.207] Entry deleted from font path.
[ 1198.207] (WW) The directory "/usr/share/fonts/X11/100dpi" does not exist.
[ 1198.207] Entry deleted from font path.
[ 1198.207] (WW) The directory "/usr/share/fonts/X11/75dpi" does not exist.
[ 1198.207] Entry deleted from font path.
[ 1198.208] (==) FontPath set to:
/usr/share/fonts/X11/misc,
/usr/share/fonts/X11/Type1,
built-ins
[ 1198.208] (==) ModulePath set to "/usr/lib/xorg/modules"
[ 1198.208] (II) The server relies on udev to provide the list of input devices.
If no devices become available, reconfigure udev or disable AutoAddDevices.
[ 1198.208] (II) Loader magic: 0x5a9008
[ 1198.208] (II) Module ABI versions:
[ 1198.208] X.Org ANSI C Emulation: 0.4
[ 1198.208] X.Org Video Driver: 25.2
[ 1198.208] X.Org XInput driver : 24.4
[ 1198.208] X.Org Server Extension : 10.0
[ 1198.213] (--) using VT number 2
[ 1198.213] (II) systemd-logind: logind integration requires -keeptty and -keeptty was not provided, disabling logind integration
[ 1198.219] (II) xfree86: Adding drm device (/dev/dri/card0)
[ 1198.220] (II) Platform probe for /sys/devices/platform/soc/5a001000.display-controller/drm/card0
[ 1198.221] (II) no primary bus or device found
[ 1198.221] falling back to /sys/devices/platform/soc/5a001000.display-controller/drm/card0
[ 1198.221] (II) LoadModule: "glx"
[ 1198.223] (II) Loading /usr/lib/xorg/modules/extensions/libglx.so
[ 1198.232] (II) Module glx: vendor="X.Org Foundation"
[ 1198.232] compiled for 1.21.1.11, module version = 1.0.0
[ 1198.232] ABI class: X.Org Server Extension, version 10.0
[ 1198.232] (II) LoadModule: "armsoc"
[ 1198.233] (II) Loading /usr/lib/xorg/modules/drivers/armsoc_drv.so
[ 1198.234] (II) Module armsoc: vendor="X.Org Foundation"
[ 1198.234] compiled for 1.21.1.3, module version = 1.4.1
[ 1198.235] Module class: X.Org Video Driver
[ 1198.235] ABI class: X.Org Video Driver, version 25.2
[ 1198.235] (II) ARMSOC: Driver for ARM Mali compatible chipsets
[ 1198.237] (WW) Falling back to old probe method for armsoc
[ 1198.237] (II) No BusID or DriverName specified - opening /dev/dri/card0
[ 1198.237] (II) Got BusID 5a001000.display-controller
[ 1198.238] (II) Opened DRM
[ 1198.238] (II) DeviceName is [/dev/dri/card0]
[ 1198.238] (II) bus_id is [5a001000.display-controller]
[ 1198.238] (II) DriverName is [stm]
[ 1198.238] (II) version is [1.0.0]
[ 1198.238] (II) Screen:0, CRTC:-1
[ 1198.238] (WW) VGA arbiter: cannot open kernel arbiter, no multi-card support
[ 1198.239] (II) ARMSOC(0): Creating default Display subsection in Screen section
"DefaultScreen" for depth/fbbpp 24/32
[ 1198.239] (**) ARMSOC(0): Depth 24, (--) framebuffer bpp 32
[ 1198.239] (==) ARMSOC(0): RGB weight 888
[ 1198.239] (==) ARMSOC(0): Using gamma correction (1.0, 1.0, 1.0)
[ 1198.239] (==) ARMSOC(0): Default visual is TrueColor
[ 1198.239] (II) No BusID or DriverName specified - opening /dev/dri/card0
[ 1198.239] (II) Got BusID 5a001000.display-controller
[ 1198.239] (II) Opened DRM
[ 1198.239] (II) DeviceName is [/dev/dri/card0]
[ 1198.240] (II) bus_id is [5a001000.display-controller]
[ 1198.240] (II) DriverName is [stm]
[ 1198.240] (II) version is [1.0.0]
[ 1198.240] (II) UnloadModule: "armsoc"
[ 1198.240] (EE) Screen(s) found, but none have a usable configuration.
[ 1198.241] (EE) Fatal server error:
[ 1198.241] (EE) no screens found(EE)
[ 1198.241] (EE) Please consult the The X.Org Foundation support at http://wiki.x.org for help.
[ 1198.241] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[ 1198.241] (EE)
[ 1198.243] (EE) Server terminated with error (1). Closing log file.
这里的问题是它找不到layout section。因此，它改用默认屏幕，但这似乎不起作用，因为它有一个usable configuration。
[ 1198.202] (==) Using config directory: "/etc/X11/xorg.conf.d"
[ 1198.202] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[ 1198.204] (==) No Layout section. Using the first Screen section.
[ 1198.205] (**) |-->Screen "DefaultScreen" (0)
[ 1198.205] (**) | |-->Monitor "<default monitor>"
[ 1198.206] (**) | |-->Device "Mali FBDEV"
[ 1198.206] (==) No monitor specified for screen "DefaultScreen". Using a default monitor configuration.
我device有这个配置
[?2004hroot@stm32-os:~# modetest -M stm
[?2004l
Encoders:
id crtc type possible crtcs possible clones
31 38 DPI 0x00000001 0x00000001
Connectors:
id encoder status name size (mm) modes encoders
32 31 connected HDMI-A-1 1210x680 7 31
modes:
index name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot
#0 1920x1080 30.00 1920 2008 2052 2200 1080 1084 1089 1125 74250 flags: phsync, pvsync; type: driver
#1 1920x1080 25.00 1920 2448 2492 2640 1080 1084 1089 1125 74250 flags: phsync, pvsync; type: driver
#2 1920x1080 24.00 1920 2558 2602 2750 1080 1084 1089 1125 74250 flags: phsync, pvsync; type: driver
#3 1280x720 60.00 1280 1390 1430 1650 720 725 730 750 74250 flags: phsync, pvsync; type: driver
#4 1280x720 50.00 1280 1720 1760 1980 720 725 730 750 74250 flags: phsync, pvsync; type: driver
#5 720x576 50.00 720 732 796 864 576 581 586 625 27000 flags: nhsync, nvsync; type: driver
#6 720x480 59.94 720 736 798 858 480 489 495 525 27000 flags: nhsync, nvsync; type: driver
props:
1 EDID:
flags: immutable blob
blobs:
value:
00ffffffffffff00506c866511100100
271b0103807944780a0dc9a057479827
12484c2108008140a940818081c0a9c0
01010101010104740030f2705a80b058
8a0020c23100001e023a801871382d40
582c4500b9a84200001e000000fc0054
434c20534d4152542054560a000000fd
00324b1e5023000a20202020202001f0
020340f257909f051420041312110302
161507060121225d625e5f6429090707
15175055170083010000e200ff6e030c
002000b84421008001020304e3050301
023a801871382d40582c4500b9a84200
001e011d007251d01e206e285500b9a8
4200001e000000000000000000000000
000000000000000000000000000000a3
2 DPMS:
flags: enum
enums: On=0 Standby=1 Suspend=2 Off=3
value: 0
5 link-status:
flags: enum
enums: Good=0 Bad=1
value: 0
6 non-desktop:
flags: immutable range
values: 0 1
value: 0
4 TILE:
flags: immutable blob
blobs:
value:
33 dithering:
flags: enum
enums: Off=0 On=1
value: 0
CRTCs:
id fb pos size
38 0 (0,0) (1280x720)
#0 1280x720 60.00 1280 1390 1430 1650 720 725 730 750 74250 flags: phsync, pvsync; type: driver
props:
24 VRR_ENABLED:
flags: range
values: 0 1
value: 0
28 GAMMA_LUT:
flags: blob
blobs:
value:
29 GAMMA_LUT_SIZE:
flags: immutable range
values: 0 4294967295
value: 256
Planes:
id crtc fb CRTC x,y x,y gamma size possible crtcs
34 0 0 0,0 0,0 0 0x00000001
formats: AR24 XR24 RG24 RG16 AR15 XR15 AR12 XR12 C8
props:
8 type:
flags: immutable enum
enums: Overlay=0 Primary=1 Cursor=2
value: 1
30 IN_FORMATS:
flags: immutable blob
blobs:
value:
01000000000000000900000018000000
01000000400000004152323458523234
52473234524731364152313558523135
41523132585231324338202000000000
ff010000000000000000000000000000
0000000000000000
in_formats blob decoded:
AR24: LINEAR(0x0)
XR24: LINEAR(0x0)
RG24: LINEAR(0x0)
RG16: LINEAR(0x0)
AR15: LINEAR(0x0)
XR15: LINEAR(0x0)
AR12: LINEAR(0x0)
XR12: LINEAR(0x0)
C8: LINEAR(0x0)
36 alpha:
flags: range
values: 0 65535
value: 65535
37 zpos:
flags: immutable range
values: 0 0
value: 0
39 0 0 0,0 0,0 0 0x00000001
formats: AR24 RG24 RG16 AR15 AR12 C8
props:
8 type:
flags: immutable enum
enums: Overlay=0 Primary=1 Cursor=2
value: 0
30 IN_FORMATS:
flags: immutable blob
blobs:
value:
01000000000000000600000018000000
01000000300000004152323452473234
52473136415231354152313243382020
3f000000000000000000000000000000
0000000000000000
in_formats blob decoded:
AR24: LINEAR(0x0)
RG24: LINEAR(0x0)
RG16: LINEAR(0x0)
AR15: LINEAR(0x0)
AR12: LINEAR(0x0)
C8: LINEAR(0x0)
41 alpha:
flags: range
values: 0 65535
value: 65535
42 zpos:
flags: immutable range
values: 1 1
value: 1
Frame buffers:
id size pitch
[?2004hroot@stm32-os:~#
问题：
startx当我写入以加载图形屏幕时，如何创建一个配置文件，让我的 Linux 内核或任何东西读取该文件？
编辑：
这发生在Ubuntu 24.04 LTS armhf
编辑2：
我试过X -configure。
[?2004hroot@stm32-os:~# X -configure
[?2004l
X.Org X Server 1.21.1.11
X Protocol Version 11, Revision 0
Current Operating System: Linux stm32-os 6.1.82 #1 PREEMPT Tue Sep 10 21:04:28 CEST 2024 armv7l
Kernel command line: root=PARTUUID=e91c4e10-16e6-4c0e-bd0e-77becf4a3582 rootwait rw console=ttySTM0,115200
xorg-server 2:21.1.12-1ubuntu1 (For technical support please see http://www.ubuntu.com/support)
Current version of pixman: 0.42.2
Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Sun Apr 21 12:47:20 2024
List of video drivers:
amdgpu
armsoc
ati
nouveau
radeon
modesetting
fbdev
vesa
(++) Using config file: "/root/xorg.conf.new"
(==) Using config directory: "/etc/X11/xorg.conf.d"
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
Number of created screens does not match number of detected devices.
Configuration failed.
(EE) Server terminated with error (2). Closing log file.
[?2004hroot@stm32-os:~#
还有/root/xorg.config.new
less /root/xorg.conf.new
[?2004l
Section "ServerLayout"
Identifier "X.org Configured"
Screen 0 "Screen0" 0 0
InputDevice "Mouse0" "CorePointer"
InputDevice "Keyboard0" "CoreKeyboard"
EndSection
Section "Files"
ModulePath "/usr/lib/xorg/modules"
FontPath "/usr/share/fonts/X11/misc"
FontPath "/usr/share/fonts/X11/cyrillic"
FontPath "/usr/share/fonts/X11/100dpi/:unscaled"
FontPath "/usr/share/fonts/X11/75dpi/:unscaled"
FontPath "/usr/share/fonts/X11/Type1"
FontPath "/usr/share/fonts/X11/100dpi"
FontPath "/usr/share/fonts/X11/75dpi"
FontPath "built-ins"
EndSection
Section "Module"
Load "glx"
EndSection
[7m/root/xorg.conf.new[27m[K
[KSection "InputDevice"
:[K
[K Identifier "Keyboard0"
:[K
[K Driver "kbd"
:[K
[KEndSection
:[K
[K
:[K
[KSection "InputDevice"
:[K
[K Identifier "Mouse0"
:[K
[K Driver "mouse"
:[K
[K Option "Protocol" "auto"
:[K
[K Option "Device" "/dev/input/mice"
:[K
[K Option "ZAxisMapping" "4 5 6 7"
:[K
[KEndSection
:[K
[K
:[K
[KSection "Monitor"
:[K
[K Identifier "Monitor0"
:[K
[K VendorName "Monitor Vendor"
:[K
[K ModelName "Monitor Model"
:[K
[KEndSection
:[K
[K
:[K
[KSection "Device"
:[K
[K ### Available Driver options are:-
:[K
[K ### Values: <i>: integer, <f>: float, <bool>: "True"/"False",
:[K
[K ### <string>: "String", <freq>: "<f> Hz/kHz/MHz",
:[K
[K ### <percent>: "<f>%"
:[K
[K ### [arg]: arg optional
:[K
[K #Option "Debug" # [<bool>]
:[K
[K #Option "NoFlip" # [<bool>]
:[K
[K #Option "DRICard" # <i>
:[K
[K #Option "BusID" # <str>
:[K
[K #Option "DriverName" # <str>
:[K
[K #Option "DRI2MaxBuffers" # <i>
:[K
[K #Option "InitFromFBDev" # <str>
:[K
[K #Option "UMP_LOCK" # [<bool>]
:[K
[K Identifier "Card0"
:[K
[K Driver "armsoc"
:[K
[KEndSection
:[K
[K
:[K
[KSection "Screen"
:[K
[K Identifier "Screen0"
:[K
[K Device "Card0"
:[K
[K Monitor "Monitor0"
:[K
[K SubSection "Display"
:[K
[K Viewport 0 0
:[K
[K Depth 1
:[K
[K EndSubSection
:[K
[K SubSection "Display"
:[K
[K Viewport 0 0
:[K
[K Depth 4
:[K
[K EndSubSection
:[K
[K SubSection "Display"
:[K
[K Viewport 0 0
:[K
[K Depth 8
:[K
[K EndSubSection
:[K
[K SubSection "Display"
:[K
[K Viewport 0 0
:[K
[K Depth 15
:[K
[K EndSubSection
:[K
[K SubSection "Display"
:[K
[K Viewport 0 0
:[K
[K Depth 16
:[K
[K EndSubSection
:[K
[K SubSection "Display"
:[K
[K Viewport 0 0
:[K
[K Depth 24
:[K
[K EndSubSection
:[K
[KEndSection
[K[?2004hroot@stm32-os:~#
我在 Linux 上使用打开文件描述 (OFD) 拥有的锁（fcntl使用命令F_OFD_SETLK）。锁定文件后，我对其进行了内存映射，然后关闭了文件描述符。另一个进程尝试锁定同一个文件，但直到第一个进程取消内存映射后才成功。看来 Linux 至少在映射仍处于活动状态时保留了对打开文件描述的引用。
POSIX.1-2024 文档mmap添加了对“与文件描述符关联的文件”的引用。
mmap() 函数应向与文件描述符 fildes 关联的文件添加额外的引用，该文件描述符上的后续 close() 不会删除该文件。当文件不再有映射时，应删除此引用。
这里的字面解释是引用文件本身，但我不知道这是否是编写文档时的意图。
我希望能够依赖这种行为。POSIX 中是否有我遗漏的地方？这可能是缺陷报告吗？如果它是 Linux 独有的，是否有任何地方提到这是他们的预期行为（并且可能是他们对 POSIX 标准的解释）？
测试程序（在其他平台上可能需要不同的功能测试宏）：
#define _GNU_SOURCE
#include <fcntl.h>
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main()
{
char filename[] = "/tmp/ofd-test.XXXXXX";
int fd = mkstemp(filename);
if (fd < 0) {
perror("mkstemp");
return 1;
}
fprintf(stderr, "created file '%s'\n", filename);
struct flock lock = {
.l_len = 0,
.l_pid = 0,
.l_whence = SEEK_SET,
.l_start = 0,
.l_type = F_WRLCK,
};
if (fcntl(fd, F_OFD_SETLK, &lock) < 0) {
perror("first lock");
return 1;
}
void *ptr = mmap(0, 1024, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (ptr == MAP_FAILED) {
perror("mmap");
return 1;
}
close(fd);
int newfd = open(filename, O_RDWR);
if (newfd < 0) {
perror("re-open");
return 1;
}
lock.l_pid = 0;
if (fcntl(newfd, F_OFD_SETLK, &lock) == 0) {
fputs("locking after mmap worked\n", stderr);
return 1;
}
perror("locking after mmap");
munmap(ptr, 1024);
lock.l_pid = 0;
if (fcntl(newfd, F_OFD_SETLK, &lock) < 0) {
perror("locking after munmap");
return 1;
}
fputs("locking after munmap worked\n", stderr);
if (unlink(filename) < 0) {
perror("unlink");
return 1;
}
return 0;
}
对我来说，输出如下：
created file '/tmp/ofd-test.Pyf3oj'
locking after mmap: Resource temporarily unavailable
locking after munmap worked
我有一个超级复杂的 bash 脚本，它从一个大型输出文件中提取结果（在 LINUX 机器上生成，以防万一这相关）。作为此过程的一部分，我使用 grep、head、tail 等的组合从这个较大的文件中提取子部分；然后将此文本子部分保存到临时文件中，然后进一步处理。我在这里提供了一个更简单的例子，这样我就可以提出我的问题，即：
我怎样才能避免保存到这个临时文件？
我想要做的是，不是将这部分文本保存到临时文件中，而是将数据子部分（包括回车符）保存到 bash 变量中，然后可以进一步处理。
问题是我编写的 bash 脚本没有“看到”回车符。在下面的示例中，我有一个文件“exampledata.data”，其中包含以下文本：
START_BLOCK #1
line a b c
line b
END_BLOCK #1
START_BLOCK #2
Line 1 2
Line 2 7
Line 3
Line 4
END_BLOCK #2
START_BLOCK #3
Line x s d e f
END_BLOCK #3
我的原始脚本（保存到临时文件）按预期工作，awk 命令正确显示每个“块”内所有行的第二个标记：
#!/bin/bash
file="examplefile.data" # File to process
totblock=`grep "START_BLOCK" $file | wc -l` # Determine number of blocks of data in file
# Current implementation - which works
for ((l=1; $l<=${totblock}; l++)); do # Loop through each block of data
echo "BLOCK "$l
# display file contents -> extract subsection of data for current block -> Remove top and bottom -> Save to temporary file
cat $file | \
sed -n '/START_BLOCK #'${l}'/,/END_BLOCK #'${l}'/p' | \
grep -Ev "START|END" > TEMPFILE
# Perform some rudimentary processing on this temporary file to check the overall process is working
awk '{print $2}' TEMPFILE
done
rm TEMPFILE
如果我尝试将本来要保存到 TEMPFILE 的内容保存到 bash 变量 (bashvar)，则所有回车符都会丢失，导致一行很长。因此，awk 命令实际上只显示第一行的第二个标记，这不是我想要的：
#!/bin/bash
file="examplefile.data" # File to process
totblock=`grep "START_BLOCK" $file | wc -l` # Determine number of blocks of data in file
# New implementation with the aim to avoid the need to write to a temporary file (TEMPFILE)
for ((l=1; $l<=${totblock}; l++)); do
echo "BLOCK "$l
# As above but rather than piping the output to a file, save it to a bash-variable
bashvar=`cat $file | \
sed -n '/START_BLOCK #'${l}'/,/END_BLOCK #'${l}'/p' | \
grep -Ev "START|END"`
# Perform the same rudimentary test to confirm the overall process is working
echo $bashvar | awk '{print $2}'
done
当我运行命令时：
realm join -U [email protected] porton.com.il --verbose
我被提示输入[email protected] 的密码。由于我想在脚本中为许多服务器运行此操作，有没有办法跳过此提示或自动从脚本发送密码（其脚本在 bash 或 csh 中运行）。
我想连接一个或多个 Wii 遥控器来读取它们的输入。从 的输出中，cat /proc/bus/input/devices我可以从 中提取数据，例如Sysfs和 输入Handlers。Handers我使用这些信息从相应的输入设备（例如 ）读取/dev/input/event17。我的问题是：如何获取相应的 MAC 地址？
一个遥控器的输出如下：
N: Name="Nintendo Wii Remote"
P: Phys=
S: Sysfs=/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/bluetooth/hci0/hci0:3/0005:057E:0306.0009/input/input29
U: Uniq=
H: Handlers=kbd event17 js0
B: PROP=0
B: EV=200003
B: KEY=10800000 0 1003000000000006 0 0 168000000000 0
B: FF=107030000 0
（一旦遥控器暂时处于非活动状态，我想通过断开它bluetoothctl disconnect {MAC-address}，但我需要区分多个遥控器......并且我不想断开错误的遥控器......）