Bash Socket Programming

Standard

From: http://hacktux.com/bash/socket


You can connect to a socket using Bash by using exec and redirecting to and from the pseudo-path /dev/tcp/<hostname>/<port> or /dev/udp/<hostname>/<port>. For instance, to connect to your localhost SSH port using TCP:

Then, use cat and echo to read or write to the socket. Here is an example read:

Notice that there is no such file as /dev/tcp or /dev/udp. Bash interprets the pseudo-path.

As another example, maybe you want to download a webpage:

Finally, let’s say you wanted to connect to an IRC server. Here is an example:

Sources

tldp.org: Advanced Bash-Scripting Guide – Chapter 29
thesmithfam.org: Bash socket programming with /dev/tcp


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Delete Files Older Than x Days on Linux

Standard

Delete Files Older Than x Days on Linux
The find utility on linux allows you to pass in a bunch of interesting arguments, including one to execute another command on each file. We’ll use this in order to figure out what files are older than a certain number of days, and then use the rm command to delete them.

Command Syntax

Note that there are spaces between rm, {}, and \;

Explanation

The first argument is the path to the files. This can be a path, a directory, or a wildcard as in the example above. I would recommend using the full path, and make sure that you run the command without the exec rm to make sure you are getting the right results.
The second argument, -mtime, is used to specify the number of days old that the file is. If you enter +5, it will find files older than 5 days.
The third argument, -exec, allows you to pass in a command such as rm. The {} \; at the end is required to end the command.
This should work on Ubuntu, Suse, Redhat, or pretty much any version of linux.

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