How to remove duplicated lines in a file
Answer:
Use the following command
sort test.txt | uniq
Jan 022010
Jan 022010
Display who are currently logged in
Answer:
Type "who" in the command shell
# who
It will display all the users currently logged in.
E.g.
john pts/0 Jan 3 00:36 (232.127.126.23)
Jan 022010
How to check if my system was just rebooted
Answer:
Use the following command
sudo last reboot
And it will show all the reboot information, e.g.
reboot system boot 2.6.27-7-server Sat Jan 2 19:03 - 20:39 (01:35)
...
Jan 022010
How to generate random password?
Answer:
Install the "makepasswd" package, for example, in Ubuntu, type
sudo apt-get install makepasswd
Then execute command
# makepasswd
ShdDHNt7z
Or you can use another tool called pwgen
sudo apt-get install pwgen
and execute
# pwgen 8 10
It will generate 10 passwords with length equal to 8
Jan 022010
How to change file's modification time?
Answer:
1. To see the current file stats, use
# stats test.txt
stat test.txt
File: `test.txt'
Size: 25557 Blocks: 56 IO Block: 4096 regular file
Device: ca01h/51713d Inode: 32714 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 1001/ user) Gid: ( 1000/ user)
Access: 2010-01-02 18:53:46.000000000 +0800
Modify: 1970-01-01 17:13:08.000000000 +0800
Change: 2010-01-02 18:53:46.000000000 +0800
2. To change the file's mtime (Modification time), use
touch -m -d '1 Jan 2006 12:34' test.txt
3. To change the file's atime (Last access time), use
touch -a -d '1 Jan 2006 12:34' test.txt
