Tag Archives: Bash

How to keep a job running in Linux

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There are many ways to keep a process running on linux but I haven’t seen any that are as easy to implement as the script below.

Basically the script does a ps ax and then a grep for your process. If it’s not running it will re-start the process.

You install the script into your crontab i.e. crontab -e

As a bonus this mechanism will re-start your process after a re-boot. Continue reading “How to keep a job running in Linux” »

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IP Setting on CentOS6 using Shell Script

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#!/bin/bash

if [ $# -eq 5 ]
then

echo ""
echo "Taking the backup and Changing the hostname from $(hostname) to $1 ..."

sed -i.bk "s/$(hostname)/$1/g" /etc/sysconfig/network

echo ""
echo "Backing up & Assigning the Static IP ..."
echo ""

cp /etc/sysconfig/network-scripts/ifcfg-$2 /etc/sysconfig/network-scripts/$2.bk

cat <<EOF > /etc/sysconfig/network-scripts/ifcfg-$2

DEVICE=$2
BOOTPROTO=static
IPADDR=$3.$4
NETMASK=255.255.255.0
GATEWAY=$3.$5
ONBOOT=yes
EOF

echo "Changing the dns ..."
echo ""

sed -i.bk "s/nameserver.*/nameserver $3.$5/" /etc/resolv.conf

echo "Adding $1 as hostname to the /etc/hosts file .."
echo ""

sed -i.bk "/$(hostname)$/d" /etc/hosts
echo "$3.$4 $1" >> /etc/hosts

echo "Restarting the Network Service, Please connect it using the new IP Address if you are using ssh ..."

service network restart

else

echo "Usage: ip.sh <hostname> <interface> <baseip> <ipaddress> <gateway/dns>"
echo "Example: ip.sh testname eth0 10.10.10 41 1"

fi
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Bash Shellshock fix with scripts for Debian, Ubuntu, CentOS and other distros. including old

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First check if your Bash is vulnerable, execute the following command-

env x='() { :;}; echo vulnerable’ bash -c ‘echo this is a test’

If your system is vulnerable, you will see:

vulnerable

this is a test

If your system is not vulnerable, you will see:

bash: warning: x: ignoring function definition attempt

bash: error importing function definition for `x’

this is a test

To check for the vulnerability CVE-2014-6271, run the following in Bash:

env X='() { (a)=>\’ sh -c “echo date”; cat echo

If your system is vulnerable, you will see:

bash: X: line 1: syntax error near unexpected toke `=’

bash: X: line 1: `’

bash: error importing function for `X’

Sun Sep 08:17:32 EST 2014

If your system is not vulernable, you will see:

date

cat: echo: No such file or directory

To test the vulnerability CVE-2014-7186, run the following in Bash:

bash -c ‘true <<EOF <<EOF <<EOF <<EOF <<EOF <<EOF <<EOF <<EOF <<EOF <<EOF <<EOF <<EOF <<EOF <<EOF’ || echo “CVE-2014-7186 vulnerable, redir_stack”

If your system is not vulnerable, you will see:

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

bash: warning: here-document at line 0 delimited by end-of-file (wanted `EOF’)

So, let’s start fixing it!

 

Below, I’ve tried to put various contributors solution to place in a single entry.

For Debian 6 (Squeeze)

 

Append this to your sources.list:

deb http://http.debian.net/debian squeeze-lts main contrib non-free

deb-src http://http.debian.net/debian squeeze-lts main contrib non-free

and then run

apt-get update

apt-get install -t squeeze-lts –only-upgrade bash Continue reading “Bash Shellshock fix with scripts for Debian, Ubuntu, CentOS and other distros. including old” »

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CRON scripts to running in seconds interval

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This problem can be solved with simple bash script. For example, if you need to run a PHP script on every 20 seconds, you can create a bash script like this:
#!/bin/bash
#Name:myscript.sh
#Desc:Run script in every 20 seconds
while (sleep 20 && php /path_to_your_script/your_script_name.php) &
do
wait $!
done
Then, make script executable, and add it to the system startup. That’s all.
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Send HTTP requests using cURL

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Reading a URL via GET:
curl http://example.com/
Defining any HTTP method (like POST or PUT):
curl http://example.com/users/1 -XPUT
Sending data with a request:
curl http://example.com/users -d"first_name=Bruce&last_name=Wayne"
If you use -d and do not set an HTTP request method it automatically defaults to POST. Performing basic authentication:
curl http://user:password@example.com/users/1
All together now:
curl http://user:password@example.com/users/1 -XPUT -d"screen_name=batman"
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