$ nice 'cal' >
$ cat
July 2006
Su Mo Tu We Th Fr Sa
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31
4.11.3. What About...
4.11.3.1. ...redirecting standard output and standard error to the same destination?
You can use the characters 2>&1 to redirect standard error to the same destination as standard output:
$ cal 17 2009 >
Notice that the order of the redirections matters. The preceding command will redirect all output to
$ cal 17 2009 2>&1 >
The 2>&1 redirection is evaluated first, so standard error is directed to the same destination as standard output (which, at that point, is the terminal); >
This construct can also be used with piping:
$ cal 17 2009 2>&1 | head -2
This will feed both the standard output and the standard error from
4.11.3.2. ...redirecting to a device?
Linux treats most devices as files, so you can redirect data to and from devices easily. This command copies the first 50 lines of the
$ head
4.11.3.3. ...splitting a pipe to send data to two destinations?
The
$ cal -y | tee
To send a copy of the data to the screen, use tee with the device file
$ cal -y | tee /dev/tty | grep Mo | head -1 >/tmp/dow-header.txt
4.11.3.4. ...piping and redirecting data that is not text?
No assumptions are made about the type of data being piped or redirected; in fact, there are many programs that are designed to work with piped graphics, audio, or video data streams. For example, this pipeline will decode a color JPEG image, scale it to half-size, convert it to grayscale, normalize it, convert it back into a JPEG, save a copy as
$ djpeg
4.11.4. Where Can I Learn More?
? The manpage for
4.12. Writing Simple Scripts