How to detect whether input is from keyboard, a file, or another process.
Useful for writing a script that can read from standard input, or prompt the user for input if there is none.
Source: LinuxQuestions.org
Last active
August 29, 2015 14:08
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| if readlink /proc/$$/fd/0 | grep -q "^pipe:"; then | |
| # Pipe input (echo abc | myscript) | |
| elif file $( readlink /proc/$$/fd/0 ) | grep -q "character special"; then | |
| # Terminal input (keyboard) | |
| else | |
| # File input (myscript < file.txt) | |
| fi | |
| # In Bash you can also use test -t to check for a terminal: | |
| if [ -t 0 ]; then | |
| # Terminal input (keyboard) - interactive | |
| else | |
| # File or pipe input - non-interactive | |
| fi |
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