input/output redirection
1. Activate the noclobber shell option.
set -o noclobber
set -C
2. Verify that noclobber is active by repeating an ls on /etc/ with redirected output to a file.
ls /etc > etc.txt
ls /etc > etc.txt (should not work)
4. When listing all shell options, which character represents the noclobber option ?
echo $- (noclobber is visible as C)
5. Deactivate the noclobber option.
set +o noclobber
6. Make sure you have two shells open on the same computer. Create an empty tailing.txt
file. Then type tail -f tailing.txt. Use the second shell to append a line of text to that file.
Verify that the first shell displays this line.
paul@deb503:~$ > tailing.txt
paul@deb503:~$ tail -f tailing.txt
hello
world
in the other shell:
paul@deb503:~$ echo hello >> tailing.txt
paul@deb503:~$ echo world >> tailing.txt
7. Create a file that contains the names of five people. Use cat and output redirection to
create the file and use a here document to end the input.
paul@deb503:~$ cat > tennis.txt << ace
> Justine Henin
> Venus Williams
> Serena Williams
> Martina Hingis
> Kim Clijsters
> ace
paul@deb503:~$ cat tennis.txt
Justine Henin
Venus Williams
Serena Williams
Martina Hingis
Kim Clijsters
paul@deb503:~$