BASH: How to Redirect Output to File, AND Still Have it on Screen
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drf@maplepark ~]$ echo 'Output from echo' >archivefile
[drf@maplepark ~]$ echo 'Output from subsequent file run' |tee -a archivefile
Output from subsequent file run
[drf@maplepark ~]$ cat archivefile
Output from echo
Output from subsequent file run
Last edited by david1941; 04-02-2011 at 03:43 PM.
Reason: fix code tags
Now, what I actually want is to Append the file each time I run a command. I have already tried this but...
$ ls >> file |tee file
This is more complicated than it looks at the first glance and you should check man bash to understand better how it works. First, | "assigns" stdout of ls to stdin of tee (see "pipeline" and then "redirection" in man bash). Then, stdout of ls is "assigned" to file (leaving stdin of tee with no input at all), so ls fills file with the list of files. Then, stdout of tee is copied to file, too. Tee receives nothing on its stdin, so it writes an empty file over file before you get any chance to read the file file.
You may want to try:
ls | tee -a file
if you want to append the list of files to file and to display it on screen at the same time.
If you have nothing better to do, you can also have fun with:
What if i redirect into a file (ls -l > log.txt) and want it to show in realtime on another console (as if the command would run locally)? 'Cat log.txt' does only show a momentary snapshot. But it should permanently put out new data once appended/logged. An example would be 'tcpdump -i eth0 -n > log.txt'.