Commands by hieuht (2)

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backup your history
simple and easy backup your history with timestamp

Search through all installed packages names (on RPM systems)
You can use wildcard with rpm search but you have to do 2 things: 1. use "-a" switch (means "all") with query ("-q") switch - argument is a pattern to use while searching for package names of all installed packages 2. protect wildcards, so that shell could not eat them - escape it with backslash ("\") or enclose all pattern between apostrophes ("'"): $ rpm -qa 'co*de' As you can see above it is possible to insert wildcards into middle of the pattern. If you want, you can add "-i" or another rpm query options, "-i" will print package information for all installed packages matching pattern.

Efficient count files in directory (no recursion)
$ time perl -e 'if(opendir D,"."){@a=readdir D;print $#a - 1,"\n"}' 205413 real 0m0.497s user 0m0.220s sys 0m0.268s $ time { ls |wc -l; } 205413 real 0m3.776s user 0m3.340s sys 0m0.424s ********* ** EDIT: turns out this perl liner is mostly masturbation. this is slightly faster: $ find . -maxdepth 1 | wc -l sh-3.2$ time { find . -maxdepth 1|wc -l; } 205414 real 0m0.456s user 0m0.116s sys 0m0.328s ** EDIT: now a slightly faster perl version $ perl -e 'if(opendir D,"."){++$c foreach readdir D}print $c-1,"\n"' sh-3.2$ time perl -e 'if(opendir D,"."){++$c foreach readdir D}print $c-1,"\n"' 205414 real 0m0.415s user 0m0.176s sys 0m0.232s

Using scapy to get the IP of the iface used to contact local gw (i.e. supposed host IP)
You need python-scapy package

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Find usb device
I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him

Advanced python tracing
Trace python statement execution and syscalls invoked during that simultaneously

Perl Simple Webserver
First we accept a socket and fork the server. Then we overload the new socket as a code ref. This code ref takes one argument, another code ref, which is used as a callback. The callback is called once for every line read on the socket. The line is put into $_ and the socket itself is passed in to the callback. Our callback is scanning the line in $_ for an HTTP GET request. If one is found it parses the file name into $1. Then we use $1 to create an new IO::All file object... with a twist. If the file is executable("-x"), then we create a piped command as our IO::All object. This somewhat approximates CGI support. Whatever the resulting object is, we direct the contents back at our socket which is in $_[0].

Load file into RAM (cache) for faster accessing for repeated usage
Best result when file size less than half of RAM size

Show simple disk IO table using snmp
Show a simple table with disk IO for the specified host. you monitor a LOT of different thing. Mostly used for MRTG and similar, but this is nice for a quick look, which disk is busy. "public" is your SNMP community ensure that snmpd is running on the host which you intend to monitor


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