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How to read a file from the file descriptor?
Reads from the file descriptor (fd) ← Opening the file descriptors for reading and writing • Home • Executes commands and send output to the file descriptor (fd) → You can use the read command to read data from the keyboard or file. You can pass the -u option to the read command from file descriptor instead of the keyboard.
How to open a file descriptor in Bash?
Bash supports the following syntax to open file for both reading and writing on file descriptor: exec fd<>fileName. File descriptor 0 is used if fd is not specified. If the file does not exist, it is created. This syntax is useful to update file.
How to find open files in a process?
If you mean that you want to find out from the shell what files a process has open then lsof -p is what you want.
How can I read a file from the keyboard?
You can use the read command to read data from the keyboard or file. You can pass the -u option to the read command from file descriptor instead of the keyboard. This is useful to read file line by line or one word at a time.
What is the file descriptor 3 assigned by default?
What you are seeing there is an artifact of the way ls (1) works: in order to read the content of the /proc/self/fd directory and display it, it needs to open that directory. That means it gets a file handle, typically the first available thus, 3.
How is the proc file system used in Linux?
The proc file system (/proc) is a pseudo-file system which is used as an interface to kernel data structures. There is a numerical subdirectory for each running process; the subdirectory is named by the process ID. Each such subdirectory contains the pseudo-files and directories.
What does the file descriptor ( FD ) in Linux mean?
Each such subdirectory contains the pseudo-files and directories. /proc/ [PID]/fd is one of such directory containing one entry for each file which the process has open, named by its file descriptor, and which is a symbolic link to the actual file.