Tag Archives: linux

[Solved] Rtthread DCM component dcm_cache_save interface Error: mkdir:/data failed

The rtthread dcm data persistence component was used in the project, but mkdir:/data failed was reported during dcm_cache_save

But this error log is not the code of this project, it is confirmed that it is the log printed inside the dcm interface

Then confirmed that the macro #define DCM_DEFAULT_STORAGE_NAME “/user/data/db/dcm” is already in rtconfig.h

Declare that this macro is also useful for business code at system startup

The final investigation is because dcm_default_storage_name needs to be assigned when the system starts, and the dcm_strg.o of the dcm component depends on

If this variable is not assigned, it will default to mkdir:/data, but if /data has no permission, it will report that error.

So dcm_default_storage_name = DCM_DEFAULT_STORAGE_NAME is solved (it needs to be called at startup)

Solve host key verification failed [valid]

Host key verification failed

When I wanted to connect to my server on the Mac, I found that there was a problem with my key, so Baidu took a look and made a record.

The first terminal is the picture of the problem, and the second terminal is a code to solve the problem

SSH keygen - R IP address you want to access
SSH keygen - R 192.168.1.5

Reference blog

Ubuntu 20.04 connection failed activation of network connection failed

Today, I tried to run wsa (Windows subsystem for Android) with win11. I found that I had to turn on Hyper-V to run. Then I found that the virtual machine VMware could not run. So I turned off Hyper-V and finally opened the virtual machine, but the network could not be connected (NAT mode is OK, but bridge mode is not)

after searching on the Internet, I changed this and that, Still No.
I fumbled and succeeded.
here is my solution:

No, as long as you have opened Hyper-V, there will be more of these two below. The default is automatic. It will give priority to these two, so we need to cancel these two checks

OK, and then enter the Ubuntu virtual machine, It is found that the network has returned to normal.

it took an afternoon to solve it. I hope I can help my friends in the future

NFS startup error: restart failed [How to Solve]

NFS startup error restart failed

Restart failed

Search for solutions

The reason is/etc/exports. A folder was previously set as a shared directory, and then the folder was deleted. Therefore, an error will occur when the NFS service is started.

The nonexistent folder needs to be deleted

Find out how to solve it

Use the VI editor to enter/etc/exports

find out whether the corresponding file paths exist in/etc/exports one by one

check and find that there is no exports folder, only the exports file

so use vi to enter the/etc/exports file, delete all

save and exit, Restart NFS successfully

Error report of mongodb startup under Linux

Version:MongoDB 5.0.3

1. Use the configuration file to start the error 1:

View log:

  The reason is an error in the configuration file:

#mongod.conf

net:

        bindIp: localhost,172.20.10.9         # 172.20.10.9 LAN IP for host computer

After 172.20.10.9 of bindip is deleted, it can be started successfully, but the host cannot connect to mongodb. At this time, by changing bindip to bindipall: true, it means that all IPS are allowed to connect to this mongodb

If you want to configure multiple IP addresses but do not want all IP addresses to be accessible, the above instructions are used, and the partition cannot be started. Query the network and learn that it is configured through [IP1, IP2], and the result is also an error:

Conclusion:       If it is only accessed locally, you can configure localhost in bindip,

                 If other IPS want to access, they can only configure bindip: 0.0.0.0 or bindipall: true

2. Use the configuration file to start error 2:

Problem cause: caused by abnormal shutdown

Solution: delete the. Lock file under the data directory, and then specify the data directory to start by — dbpaht or add the — repair parameter. After successful startup, start it by using the configuration file method

3. Add in replica set   No response when arbitrating nodes

Problem: by executing the shell in the master node, rs.addarb (host: port) does not respond, and the arbitration node cannot be added. At this time, the version is 5.0.3

Solution: reduce the version to 4.0.1

[Solved] Vermagic error and signature error in insmod

Handling of vermagic errors when insmod drives.
uname -a to see the vermagic on the environment
If the driver code is consistent, you can force to modify the UTS_RELEASE macro in include/generated/utsrelease.h to be consistent with the environment, and then compile the KO.
Signature error: signature and/or required key missing – tainting kernel
Reason: The kernel is enabled for signing, the driver is not signed.
Signature-related options in the kernel.
CONFIG_MODULE_SIG_FORMAT=y
CONFIG_MODULE_SIG=y
#CONFIG_MODULE_SIG_FORCE is not set
CONFIG_MODULE_SIG_ALL=y
#CONFIG_MODULE_SIG_SHA1 is not set
#CONFIG_MODULE_SIG_SHA224 is not set
#CONFIG_MODULE_SIG_SHA256 is not set
#CONFIG_MODULE_SIG_SHA384 is not set
CONFIG_MODULE_SIG_SHA512=y
CONFIG_MODULE_SIG_HASH=“sha512”
CONFIG_MODULE_SIG_KEY=“certs/signing_key.pem”
Signature method:
./scripts/sign-file sha512 ./certs/signing_key.pem ./certs/signing_key.x509 drivers/xxx.ko

Petalinux-boot –jtag error [How to Solve]

petalinux-boot –jtag –u-boot –hw_server-url TCP:ubuntu:3121
Using the command as above will report an error similar to the one below.

Solution:
Set the compatibility of the virtual machine’s USB device to USB3.1, because the physical USB port my computer is connected to is USB3.1.

INFO: Sourcing build tools
INFO: Launching XSDB for file download and boot.
INFO: This may take a few minutes, depending on the size of your image.
rlwrap: warning: your KaTeX parse error: Expected ‘EOF’, got ‘#’ at position 170: … “name =~ “arm*#̲0″”. available …params(filter)”. available targets:$target_list””
(procedure “targets” line 177)
invoked from within
“targets -set -nocase -filter {name =~ “arm*#0”}”
(file “/tmp/tmp.tUZ8sEM2Wm” line 3)
INFO: The XSDB log is as follows

Raspberry pie startup self startup opencv program script and error analysis

1. Make test script

First, we need to make a script to test whether the self startup is effective.

pi@raspberry :~ $ nano /home/pi/start.sh

The contents of start.sh are as follows:

/usr/bin/python3 /home/pi/GeometryOperations.py

Here, you must pay attention to the use of absolute paths, otherwise there is a probability that the load will fail.

Then add an execution file to the script file

pi@raspberry :~ $ chmod 777 start.sh

Test the script function

pi@raspberry :~ $ ./start.sh

If you observe that the program is running normally, you can continue to the next step

2. Add self start

Modify rc.local file

pi@raspberry :~ $ sudo nano /etc/rc.local

Find exit 0 in the text. The code added before will be executed at startup. Add a line of code before exit 0:

su pi -c “exec /home/pi/start.sh &”

CTRL + O to save, Ctrl + X to exit and restart.

pi@raspberry :~ $ sudo reboot

After restart, the program can run.

3.DEBUG

If the raspberry pie does not respond after restart, you can check the status of RC local through systemctl

pi@raspberry :~ $ sudo systemctl status rc-local

After you go in, you can see the status of each step after you start up and check where the error will be reported.

4. Possible error reports

Process:454 ExecStart=/etc/rc.local start (code=exited,status=1/FAILURE)

This error is probably due to the script file
if you just start, you must write the file path as an absolute path, otherwise an error will be reported.

error: (-2:Unspecified error) Can’t initialize GTK backend in function ‘cvInitSystem’

This error will be reported if the self startup program contains code with window operation such as OpenCV

The reason is caused by the following sentence

su pi -c “exec /home/pi/start.sh &”

If your command needs to run for a long time (such as an endless loop) or cannot exit after running, you must ensure that the “& amp;” symbol is added at the end of the command to make the command run in its background

If the code contains window interface operations similar to the following

cv2.namedWindow(‘Cap’)
cv2.imshow(‘Cap’, frame)

It will conflict with the background operation, so that the back end of GTK cannot be initialized and an error will be caused
the solution is to delete all the operations related to the interface and window, and the program can run well!

error: expected ‘；‘ at end of member declaration and expected ‘)‘ before ‘&‘ toke Errors

error: expected ‘;’ at end of member declaration
error: expected ‘)’ before ‘&’ Token
error reporting

When developing c + + in Linux environment, the following compilation errors or other inexplicable errors occur while ensuring that there are no errors in the code

	error: expected ';' at end of member declaration
	error: expected ‘)’ before ‘&’ toke

Solution:
check whether the header file contains circularly. For example, a.cpp contains B.H, b.cpp contains C.H, and c.cpp contains A.H to form a ring. In this case, an error will be reported.