[olug] Unix Tip: GET YOUR IP-ADDRESS (long explanation)

[Daniel Pfile]

Hmm ok... Half to be a smart ass, half to show people just why the 
command line is cool... This does explain why that learning the bash 
shell book is always near Vince. Please don't nitpick, this is kinda 
hard to explain in english, that's why programing languages exist.

[ $# -gt 0 ]

If there are more than 0 positional parameters .

&&  (

And this works:

while [ "$1" ];

Loop through the params

do ( [ -f $1 ]

Do this if the argument is a file

&& [ "$( file $1 | grep text)" ] )

The results of running the file command on the argument contains the 
word 'text'

&& ( echo -e

and this echo, grep, wc, tr group of commands work

"$( grep -vE '^[[:space:]]*#|^[[:space:]]*$' $1

Print out anything in that file that doesn't either contain a comment: 
'^[[:space:]]*# or a blank line: ^[[:space:]]*$

| wc -l

Count the number of lines in that output

| tr -d '[[:space:]]' )\t$1" );

Convert the output of spaces in wc -l into tabs.

shift;

Next please

done )

Done with the do.

|| echo "Usage: $0 <file> [file file file...]"

Since there were less than 0 parameters, show the user the usage of the 
script.

Do I get a cookie Vince?

-- Daniel

On Thursday, March 20, 2003, at 04:20 PM, Vincent wrote:

> Would you provide a long explanation for this one-line script ?  :)
>
> [ $# -gt 0 ] && ( while [ "$1" ]; do ( [ -f $1 ] && [ "$( file $1 | 
> grep text)" ] ) && ( echo -e "$( grep -vE
> '^[[:space:]]*#|^[[:space:]]*$' $1 | wc -l | tr -d '[[:space:]]' 
> )\t$1" ); shift; done ) || echo "Usage: $0 <file> [file file file
> ...]"
>
>
>
> ----- Original Message -----
> From: "Eric Penne" <epenne at olug.org>
> To: <olug at olug.org>
> Sent: Thursday, March 20, 2003 2:11 PM
> Subject: Re: [olug] Unix Tip: GET YOUR IP-ADDRESS (long explanation)
>
>
>> ifconfig | grep "inet addr" |  grep -v "127.0.0.1" | awk '{print 
>> $2;}' |
>> awk -F':' '{print $2;}'
>>
>>
>> Here is a rundown on this command for the newbies.
>>
>> 1) ifconfig is usually located in /sbin/ifconfig shows the network
>> interfaces that are up and how they are configured.
>>
>> 2) grep pulls lines out of the ifconfig info that contain inet addr
>>
>> 3) grep -v inverts.  It prints all the lines that don't have 127.0.0.1
>> in them.
>>
>> 4) awk looks at the info and pulls the second field out, where the
>> fields are separated by whitespace by default.
>>
>> 5) Then awk -F':' is used again to pull the second field out, where 
>> the
>> fields are separated by a colon.
>>
>> The individual outputs follow:
>>
>> 1)
>>
>> eth0      Link encap:Ethernet  HWaddr 00:80:AD:0C:BA:43
>>           inet addr:192.168.1.42  Bcast:192.168.255.255
>> Mask:255.255.0.0 UP BROADCAST RUNNING MULTICAST  MTU:1500
>> Metric:1
>>           RX packets:34866 errors:0 dropped:0 overruns:0 frame:0
>>           TX packets:5882 errors:0 dropped:0 overruns:0 carrier:0
>>           collisions:0 txqueuelen:100
>>           RX bytes:7133322 (6.8 MiB)  TX bytes:850473 (830.5 KiB)
>>           Interrupt:3 Base address:0xd800
>>
>> lo        Link encap:Local Loopback
>>           inet addr:127.0.0.1  Mask:255.0.0.0
>>           UP LOOPBACK RUNNING  MTU:16436  Metric:1
>>           RX packets:8 errors:0 dropped:0 overruns:0 frame:0
>>           TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
>>           collisions:0 txqueuelen:0
>>           RX bytes:400 (400.0 b)  TX bytes:400 (400.0 b)
>>
>> 2)
>>           inet addr:192.168.1.42  Bcast:192.168.255.255
>> Mask:255.255.0.0 inet addr:127.0.0.1  Mask:255.0.0.0
>>
>> 3)
>>           inet addr:192.168.1.42  Bcast:192.168.255.255
>> Mask:255.255.0.0
>>
>> 4)
>> addr:192.168.1.42
>>
>> 5)
>> 192.168.1.42
>>
>>
>> Now don't we all love the pipe command.  Hopefully if you are having
>> trouble with the above command this explanation can step you through 
>> the
>> issues.
>>
>> Eric
>>
>>
>>
>> _______________________________________________
>> OLUG mailing list
>> OLUG at olug.org
>> http://lists.olug.org/mailman/listinfo/olug
>>
>
> _______________________________________________
> OLUG mailing list
> OLUG at olug.org
> http://lists.olug.org/mailman/listinfo/olug