Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Code formatting and indentation in VIM
Answer:
Vim support code formatting and auto indentation - if you tell Vim to know the filetype (either by file extension, or by setting the filetype)
e.g. A simple C program (test.c)
#include
main()
{
for(int i=0;i<10;i++)
{
printf ("Hello World!\n");
}
}
Then type following in Vim command mode (by pressing Esc):
gg=G
Now the code will be formatted to:
#include
main()
{
for(int i=0;i<10;i++)
{
printf ("Hello World!\n");
}
}
Write Python script using utf-8
Answer:
If you have UTF-8 characters in your Python script, you need to declare the following line at the beginning of your script:
# -*- coding: utf-8 -*-
Multiple separators in awk
Answer:
Sometimes when you split a string using awk, you need to support more than 1 separators, you can use the -F option.
E.g.
# cat foo.txt | awk -F "[ ?]" '{print $7}'
Now the awk split by a space and by a ?.
Add a user to group in Linux
Answer:
To add a user to a group (supplementary), you can use the command below:
e.g.
# useradd -G admin john
If you want to change the user's primary group, you can use
e.g.
# useradd -g admin john
Check for the number of connection from a particular IP address
Answer:
You can check the total number of connections from a particular IP address:
# netstat -ntu | awk '{print $5}'| cut -d: -f1 | sort | uniq -c | sort -nr | more
It will give something like:
25 192.168.1.2
13 192.168.1.3
..
