Commands by pung96 (4)

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Sniffing network to generate a pcap file in CLI mode on a remote host and open it via local Wireshark ( GUI ).
Then hit ^C to stop, get the file by scp, and you can now use wireshark like this : $ wireshark /tmp/sniff.pcap If you have tshark on remote host, you could use that : $ wireshark -k -i

Execute a command with a timeout
In this example the command "somecommand" will be executed and sent a SIGALARM signal if it runs for more than 10 seconds. It uses the perl alarm function. It's not 100% accurate on timing, but close enough. I found this really useful when executing scripts and commands that I knew might hang E.g. ones that connect to services that might not be running. Importantly this can be used within a sequential script. The command will not release control until either the command completes or the timeout is hit.

find builtin in bash v4+
This command will give you the same list of files as "find /etc/ -name '*killall' | xargs ls -l". In a simpler format just do 'ls /etc/**/file'. It uses shell globbing, so it will also work with other commands, like "cp /etc/**/sshd sshd_backup".

Make redirects to localhost via /etc/hosts more interesting
Normally when a site is blocked through /etc/hosts, traffic is just being redirected to a non-existent server that isn't going to respond. This helps get your point across a little more clearly than a browser timeout. Of course you could use any number of codes: http://en.wikipedia.org/wiki/List_of_HTTP_status_codes Obviously, this command can be added to init-rc.d, and more sophisticated responses can be given. Seems noteworthy to mention that the information sent from the browser can be parsed using the bash READ builtin (such as 'while read -t 1 statement; do parsing'), and the connection stays open until the script exits. Take care that you must use EXEC:'bash -c foo.sh', as 'execvp' (socat's method for executing scripts) invokes 'sh', not 'bash'.

What is my public IP-address?
Very effective, use only DNS protocol. The @ part is optional if you already set opendns servers as default ns servers.

Octal ls
Do ls with permissions written in octal form.

Synchronize date and time with a server over ssh
using -u is better for standardizing date output and timezones, for servers in different timezones.

List files older than one year, exluding those in the .snapshot directory
Useful when you want to cron a daily deletion task in order to keep files not older than one year. The command excludes .snapshot directory to prevent backup deletion. One can append -delete to this command to delete the files : $ find /path/to/directory -not \( -name .snapshot -prune \) -type f -mtime +365 -delete

Copy a file over SSH without SCP

diff current vi buffer edits against original file

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