seq

The "seq" command outputs a sequence of numbers. You control the start, end and increment. It's useful to control loops:

 for i in `seq 1 20`
 do
   # do something useful 
   echo $i
 done
 

And to generate numbers you are too lazy to calculate in your head:

$ seq -s " " 1 .375 15
1 1.375 1.75 2.125 2.5 2.875 3.25 3.625 4 4.375 4.75 5.125 5.5
5.875 6.25 6.625 7 7.375 7.75 8.125 8.5 8.875 9.25 9.625 10 10.375
10.75 11.125 11.5 11.875 12.25 12.625 13 13.375 13.75 14.125 14.5
14.875
 

Notice the -s " "? Without that, the numbers would have printed down the screen in one column. This is also good for other odd tasks with a little help from "printf":

$ printf %x' ' `seq -f %1.f 1024 1024 16384`
400 800 c00 1000 1400 1800 1c00 2000 2400 2800 2c00 3000 3400 3800 3c00 4000
 

See Bash 3.00 brace expansion also.

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