Force Umount if Busy

Posted on by Ulysses

If device is busy and you can’t umount it, try it with -l option (lazy unmount). Or you can force it.

# standard
umount /mnt/data
# lazy umount
umount -l /mnt/data
# force
umount -f /mnt/data

Lazy unmount is safer since it will detach immediately and clean up all references to the file system. Force is a bit more drastic.

Run Shell Script From Your Website

Posted on by Ulysses

Here’s how to run a shell script from your website. You’ll need 2 files.

Here’s the contents of foo.php. Wrap your output with ‘pre’ for better formatting.

<?php
$output = shell_exec('/var/www/html/bar.sh 2>&1');
echo "$output";

Here’s the content of bar.sh. Output will be displayed on web page.

#!/bin/bash
now="$(date +'%y%m%d')"
echo $now
aws s3 ls

Phpinfo Blank Page

Posted on by Ulysses

Here’s how to fix when phpinfo is displaying a blank page. The install is missing this php module.

apt install php libapache2-mod-php

Restart after install.

service apache2 restart

AWS Security Groups IP Cidr

Posted on by Ulysses

Here’s how to search for AWS Security Groups containing this IP Cidr.

aws ec2 describe-security-groups \
--filter Name=egress.ip-permission.cidr,Values='10.8.8.8/32' \
--query "SecurityGroups[*].{Name:GroupName}" \
--output text \
--profile default \
--region us-east-1

Search with ports.

aws ec2 describe-security-groups \
--filter Name=egress.ip-permission.cidr,Values='10.8.8.8/32' \
         Name=egress.ip-permission.from-port,Values='22' \
         Name=egress.ip-permission.to-port,Values='22' \
--query "SecurityGroups[*].{Name:GroupName}" \
--output text \
--profile default \
--region us-east-1

Query will only display the Security Group name.