Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Extract column data using awk
Answer:
A simple awk command print the 1st column of top command
# top -bc -n1 | awk '{print $1}'
If you want to specify the field separator, you can do the following
# awk -F':' '{print $1}' /etc/passwdWhich print the 1st column of file /etc/password, as if they are split by :
Print a particular column data using awk
Answer:
Consider you have a file text.txt like below
1 one
2 two
3 three
How would you only print the second column?
It can be easily done using awk
# awk '{print $2}' text.txt
one
two
three
Try the above command with $1, $2, $3 etc.
Generate random number in Linux
Answer:
To generate a random number from 1 to 100, you can use the following simple command
# echo $((RANDOM%100+1));
76
You can replace 100 by the maximum value, and 1 by the minimum value.
How to get the PID in current bash shell script
Answer:
Use the special variable $$, you can get the PID (Process ID) of the current bash shell script
#/bin/bash
echo $$;
The above script will print the PID to the standard out.
Serve current directory using HTTP with a single command
Answer:
Sometimes, you want to share some files in a given directory in your Linux system to other people, you might consider setup a NFS, Samba, FTP or so.
However, the easiest method is to export the directory using HTTP, with the help of Python.
E.g.
# cd /data/
python -m SimpleHTTPServer
Serving HTTP on 0.0.0.0 port 8000 ...
Now people can access the web server at port 8000 of your system's IP address, to access the /data directory.
