Commands by migueldiab (1)

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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.

Localize provenance of current established connections
Sample command to obtain a list of geographic localization for established connections, extracted from netstat. Need geoiplookup command ( part of geoip package under CentOS)

See entire packet payload using tcpdump.

send a file or directory via ssh compressing with lzma for low trafic

shut of the screen.

Fake system time before running a command
Fake system time before running any command.

Insert a line at the top of a text file without sed or awk or bash loops
Yet another way to add a line at the top a of text file with the help of the tac command (reverse cat).

Command line calculator
This function defines a command line calculator that handles everything pythons math module can handle, e.g. trigonometric functions, sqrt, log, erf, ... (see http://docs.python.org/library/math.html). It even knows about the constants pi and e.

check open ports without netstat or lsof

Find broken symlinks
This is much safer than using -L, because it will not follow links that point to places outside the target directory subtree (CWD, in this case). See here for explanation: http://unix.stackexchange.com/a/38691/9382


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