Unability to open generalised "file descriptor" files eg: /proc/self/fd/xxx

[etosan]

Description

Many unices and unix-like OS-es support special directory in /proc (or elsewhere) to open inherited parent's proces file descriptors as files.

This is often used by advanced shell sub process redirection (bash, zsh and other more advanced shells).

Example:

$ nano <(ls) 
# "opens" directory listing as editable buffer (incoming as "descriptor" file from shell, containing actual output of `ls`)

Unfortunately with micro this fails:

: micro <(ls)                 
Error: /proc/self/fd/11 is not a regular file and cannot be opened

Press enter to continue

micro is probably doing regular file check on it's input file argument and raw file descriptor fails this.
This might be some kind of protection.

However this should be at least specialcased for file prefixes like /proc/self/fd/* on linux, to allow for shell sub-process redirection to work.

Environment

• Version:
• OS:
• Terminal:

[dmaluka]

/proc/*/fd/* files are simply symlinks which point to corresponding files opened by corresponding file descriptors of the given process, right? So, which file does your /proc/self/fd/11 symlink point to? Micro says: Error: /proc/self/fd/11 is not a regular file and cannot be opened so I assume that is literally what is happening: this file opened by your process with fd=11 is not a regular file (i.e. it is a character device file, or a block device file, or a FIFO, or a socket, and so on), and micro doesn't currently support editing such files.

IOW, you'll see the same error message if you try to open /dev/null, for example.

I've just tried the following: run tail -F /etc/hosts, and then in another terminal run micro /proc/$PID/fd/$FD, where $PID is the pid of the tail process, and $FD is the file descriptor of /etc/hosts opened by it. And the result is: micro successfuly opens /etc/hosts for me. Because /etc/hosts is a regular file.