Linux easy (forgotten) shortcut command summary

1. xrandr: view supported resolutions
2. xrandr -s xxxxx: set resolution
3. The header file uses <> to indicate that the header file is found in the /usr/include or /usr/local/include directory by default, and "" means to search in the current directory first, and if not found, go to the above directory to find it.
4. ./a.out 10 >>test.ret.txt & write a test file, enter the number of runs 10, print the result and append it to test.ret.txt, & means running in the background, and return the pid number
5. grep "struct sockaddr_in{" * -nir means to find the required content in the current path, n means to print the line number, i means case insensitive, r means recursive
6. The .sh file is equivalent to an executable, command-line script file.
7. Find a specific file, use find and grep together, find|grep XXX approximate path -nir
8. file xxx: view the properties of the file
9. -I : specify the header file directory
10. -L: Specify the library file directory
11. uname -r: View system version
12. du View file size
13. md5sum: View the value of md5 and compare to ensure that the file is not damaged during copying
14. df -T: View file system (Raspberry Pi)
15. sudo mknod +name +major device number+minor device number: Manually generate devices
16. tar xvf : decompress the .tar file
17. chdir; change the current main program directory, system() changes the shell script directory, chdir should use an absolute path
18. pgrep + XXX: match and print the specific pid number