Bash shell read error: 0: Resource temporarily unavailable

Question

When writing a bash script. Sometimes you are running a command which opens up another program such as npm, composer.. etc. But at the same time you need to use read

Answer 1

The answers here which suggest using redirection are good. Fortunately, Bash's read should soon no longer need such fixes. The author of Readline, Chet Ramey, has already written a patch: http://gnu-bash.2382.n7.nabble.com/read-may-fail-due-to-nonblocking-stdin-td18519.html

However, this problem is more general than just the read command in Bash. Many programs presume stdin is blocking (e.g., mimeopen) and some programs leave stdin non-blocking after they exit (e.g., cec-client). Bash has no builtin way to turn off non-blocking input, so, in those situations, you can use Python from the command line:

$ python3 -c $'import os\nos.set_blocking(0, True)'

You can also have Python print the previous state so that it may be changed only temporarily:

$ o=$(python3 -c $'import os\nprint(os.get_blocking(0))\nos.set_blocking(0, True)')
$ somecommandthatreadsstdin
$ python3 -c $'import os\nos.set_blocking(0, '$o')'