Redirect stdout and stderr of cmd1 to stdin of cmd2 (bash 4.0+ only). Use cmd1 2>&1 | cmd2 for older bashes.

File descriptors 0,1 and 2 are special and assumed to represent STDIN, STDOUT and STDERR DOUT/STDERR to be something else without the program knowing! Pipes are how terminal support …

2). The semantics of this shell should be that all simple commands will send the stderr to the same ace. The example given above can be modified to support stderr redire

Here, the stderr portion of the command is sent to stdout, if you pipe to less, you'll see that lines that normally 'dissapear' (as they are written to stderr) are being kept now (because they're on stdout).

Redirect stdout and stderr of cmd1 to stdin of cmd2 (bash 4.0+ only). Use cmd1 2>&1 | cmd2 for older bashes.

Most commands receive input from stdin (so, pipe) and file, eg. Some receive input only from stdin and not from file, eg. Some receive input neither from stdin nor from file, eg. When pipe is not enough! …

perror() appends an error-specific message to the text provided and prints it to stderr You may also print additional error messages to stderr with fprintf(stderr, ...) Good programming practice: check the …