Filehandles
Filehandles are symbolic IDs for files and pseudo-files that are set up each time the kernel starts a process. These numbers are what the process uses to write output and read input. Three filehandles are opened by default:
| Filehandle | Meaning |
|---|---|
| F.H. 0 | STDIN. This is where standard input comes from. This is normally the keyboard, but it can be redirected to read from a file or some other source. |
| F.H. 1 | STDOUT. This where standard output goes. It is normally the screen, but as you have seen it can be redirected. |
| F.H. 2 | STDERR. This is where standard error messages go. Once again, this is normally the screen, but it can also be redirected. |
Filehandles can be used in shell programs to make your programs both more efficient and easier to write. ...
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