Ping

ICMP echo request alias ping:

perl -MNet::Ping -lne 'print "$_: ", scalar Net::Ping->new( "icmp" )->ping( $_ )' hosts.txt

TCP based ping using port 80:

perl -MNet::Ping -lne '$p = Net::Ping->new; $p->port_number( 80 );
                       print "$_: ", scalar $p->ping( $_ )' hosts.txt

Blocking Traffic Using Null Route

Blocking network traffic for a specific host without using iptables:

ip route add blackhole 10.0.0.1/32

To remove the rule:

ip route del blackhole 10.0.0.1/32

Compared to iptables a null route has no effect on loopback addresses (127.0.0.0/8).

Erase Old Files

Erase files older than 7 days:

find -mtime +7 -exec rm -rf {} \;

Git Tagging

Add an annotated tag:

git tag -a v1.0.0 -m 'release 1.0.0'

Push tag changes to remote repositories:

git push --tags

Remove a tag:

git tag -d v1.0.0

Remove a tag from remote repositories:

git tag -d v1.0.0
git push origin :refs/tags/v1.0.0