Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Parallel downloader in Linux
Answer:
wget is perhaps the most popular downloader (command) in Linux, but it cannot establish more than 1 connection to the server for max. speed.
Axel is a lightweight download accelerator for Linux that solve the problem.
To install under Ubuntu:
# sudo apt-get install axel
To download a file by using 10 connections
# axel -n 10 http://www.example.com/file.gz
That's very cool!
Join lines on a common field
Answer:
Suppose you have two files
file1.txt
john b
mark c
peter a
file2.txt
john 2
mark 3
peter 1
You can to join two files by the first column, to become
john b 2
mark c 3
peter a 1
It is easy with the join command
# join file1.txt file2.txt
Remark: You would need to sort the file and make each column an unique line first.
How to dump an MySQL/InnoDB database
Answer:
To do a point-in-time SQL dump of a InnoDB database, use the mysqldump command with the --single-transaction flag
# mysqldump --master-data=2 --single-transaction huge_db > backup.sql
The binlog position will be written in the backup.sql, which is very useful for database recovery if needed.
How to force re-download a file using wget?
Answer:
Use the -nc flag, e.g.
# wget -nc ftp://sunsite.doc.ic.ac.uk/ls-lR.Z
How to mount an ISO file in Linux
Answer:
1. Create the mount point
# mkdir -p /mnt/iso
2. Mount the iso file using the mount command
# mount -o loop dvd.iso /mnt/iso
