Directory Inode vs Regular File Inode
I believe it’s the mode of the inode… To access the field see stat(2) man page: Here is some example code from the Linux driver for minix FS:
linux
boto3 client NoRegionError: You must specify a region error only sometimes
One way or another you must tell boto3 in which region you wish the kms client to be created. This could be done explicitly using the region_name parameter as in: or you can have a default region associated with your profile in your ~/.aws/config file as in: or you can use an environment variable as in: but you do need to … Read more
Does connect() block for TCP socket?
There’s hardly any “immediately” regarding networking, stuff can be lost on the way, and an operation that should be performed immediately in theory might not do so in practice, and in any case there’s the end to end transmission time. However connect() on a TCP socket is a blocking operation unless the socket descriptor is … Read more
Who can access a file with octal permissions “000” on Linux/UNIX?
root can do everything, others (with userid != 0) can’t do anything. But anyone who has write access to the containing folder is allowed to delete the file. The owner can of course always change the flags and regain access anytime.
Install tkinter for Python
It is not very easy to install Tkinter locally to use with system-provided Python. You may build it from sources, but this is usually not the best idea with a binary package-based distro you’re apparently running. It’s safer to apt-get install python-tk on your machine(s). (Works on Debian-derived distributions like for Ubuntu; refer to your package manager … Read more
Python subprocess.Popen “OSError: [Errno 12] Cannot allocate memory”
As a general rule (i.e. in vanilla kernels), fork/clone failures with ENOMEM occur specifically because of either an honest to God out-of-memory condition (dup_mm, dup_task_struct, alloc_pid, mpol_dup, mm_init etc. croak), or because security_vm_enough_memory_mm failed you while enforcing the overcommit policy. Start by checking the vmsize of the process that failed to fork, at the time of the fork attempt, and then compare to the amount of free memory (physical and swap) as it … Read more
WSL – GEDIT Unable to init server: Could not connect: Connection refused
You need an X server to run graphical applications like gedit. I use VcXsrv or Xming on my Windows desktops, both are very small and easy to install, but there exist other servers like Cygwin/X. Short instructions for VcXsrv/Xming: download and install the Windows package start XLaunch or Xming export the DISPLAY variable in your WSL terminal and start geditexport DISPLAY=0:0 … Read more
using pip3: module “importlib._bootstrap” has no attribute “SourceFileLoader”
Faced the same problem. I think this is because python3.6 and pip3 were installed from different sources. I suggest using python’s inbuilt facility to install pip i.e This should install pip3 and pip3.x where x in python3.x. Same works for python2 also.
The difference between stdout and STDOUT_FILENO
stdout is a FILE* “constant” giving the standard outout stream. So obviously fprintf(stdout, “x=%d\n”, x); has the same behavior as printf(“x=%d\n”, x);; you use stdout for <stdio.h> functions like fprintf, fputs etc.. STDOUT_FILENO is an integer file descriptor (actually, the integer 1). You might use it for write syscall. The relation between the two is STDOUT_FILENO == fileno(stdout) (Except after you do weird things like fclose(stdout);, or perhaps some freopen after some fclose(stdin), which you should … Read more
X11 forwarding request failed on channel 0
Adding the -v option to ssh when trying to log in will give a lot of debug information which might give a clue to exactly what the problem is, like for instance which in my case installing xauth on the server fixed the issue.