Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Split on specific characters on Bash Script's for loop
Answer:
If you want to Bash script's for loop to split on non white-space characters, you can change the IFS, e.g.
#!/bin/bash
IFS='-'
list="a-b-c-d-e"
for c in $list; do
echo $c
doneThe above script will split on the character '-'
E.g.
# ./test.sh
a
b
c
d
e
Sending email using raw SMTP commands
Answer:
You can send email(s) by connecting to your SMTP server, and using raw SMTP commands.
E.g. assume your SMTP is localhost, listening port 25, enter the commands in bold
# telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.localdomain.
Escape character is '^]'.
220 smtp.example.com ESMTP Postfix (Ubuntu)
helo localhost
250 smtp.example.com
mail from: john@example.com
250 2.1.0 Ok
rcpt to: mary@example.com
250 2.1.5 Ok
data
354 End data with
This is a test mail
.
250 2.0.0 Ok: queued as BA2FD1DB96
quit
221 2.0.0 Bye
Connection closed by foreign host.
Convert all text in a file from upper-case to lower-case
Answer:
Just one command needed:
# tr '[:upper:]' '[:lower:]' < input.txt
Removed opened port in ufw
Answer:
If you have opened a port using the ufw command in Ubuntu, but now you want to delete it, you can..
# sudo ufw delete allow 8080/tcp
And then do a reload
# # sudo ufw reload
That's all.
Combine multiple images into a single image with ImageMagick
Answer:
With the powerful ImageMagick program, we can easily handle common graphics tasks using command only.
For example, to combine multiple images into a single image, we need just one command:
# convert file1.jpg file2.jpg file3.jpg +append -quality 90 'output.jpg'
The above command (file1.jpg file2.jpg file3.jpg) into the file output.jpg with quality set to 90.
