Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
How to avoid command being saved to shell history
Answer:
Firstly, you need to set the Bash shell environment variable to tell the shell to ignore the history if the command is starting with a particular character, e.g. a space in our case below.
# export HISTIGNORE="&:[ ]*"
Then, type the command start with a space
# who
And verify using the history command
# history
Quick and easy SMTP server with Python
Answer:
You can start a Python SMTP server, with only a single command, without installing any additional software in modern Linux.
E.g.
sudo python -m smtpd -n -c DebuggingServer localhost:25
Best way to kill all child processes forked by a given program
Answer:
Firstly, find the process group leader (i.e. master process that forked other processes) of the program, e.g. apache2
# sudo ps x -o "%p %r %y %x %c " | grep apache2
14787 14787 ? 00:00:00 apache2
To verify if it is the process leader.
# pgrep apache2 | sort -n | head -n1
14787
To issue kill to all the members in the process group
# kill -9 -14787
Add a user that can gain root privileges in Ubuntu
Answer:
You have created a user, and now you want to make this user (e.g. peter as an example) can gain root privileges.
Firstly, check your /etc/sudoers file
# sudo cat /etc/sudoers
You might found the following lines
# Members of the admin group may gain root privileges
%admin ALL=(ALL) ALL
john ALL=(ALL) ALLMethod 1
If you have the line %admin ALL=(ALL) ALL, then you can add the user (e.g peter) to the admin group using the command:
# sudo usermod -g admin peter
Method 2
Or you can edit the file /etc/sudoers to add your account manually
# sudo visudo
Append peter ALL=(ALL) ALL at the end..
%admin ALL=(ALL) ALL
john ALL=(ALL) ALL
peter ALL=(ALL) ALLAre there any Linux equivalent of the Mac OS X "open" command?
Answer:
The Mac OSX's open command is a very handy tool for opening file, without the need to sepcify the program name.
In Linux, you have two choices:
1. xdg-open
# xdg-open test.html
2. see
# see test.html
Both command will open the file by your default web browser.
