Linux Ask!

Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.

Aug 232011

Check if a file exist in Bash Shell


The following script demonstrates how to check if a file exist, using shell (Bash) script


if [ -e test.txt ]
  echo 'The file exists.'
  echo 'The file does not exist.'
Apr 022011

How to rename a user in Linux?


Firstly, you need to have a account with root privileges (You cannot change the account name if you have this user currently logged in)

To rename a user, do the following steps:

1. Rename user

# sudo usermod -l new_user -d /home/new_user -m old_user

2. Update group (Usually the same as user name)

# sudo groupmod -n new_user old_user

That's all.

Dec 262010

Display timestamp information in command history


When using the history command, it only shows the command number and the command itself. But sometimes it is useful to know when this command was executed, i.e. the timestamp. To do so, following the instructions below:

# export HISTTIMEFORMAT='%F %T '

Then type history again

# history
 260  2010-12-23 19:22:07 ls
 261  2010-12-23 19:22:07 pwd

That's all.