Create a random character text file using Linux shell

Here is a nice trick on how to create a dummy character text file consisting of any chosen or random characters. In the first example we will create and simple file consisting of a single character X with a size of 1000 bytes:

$  < /dev/urandom tr -dc "X" | head -c1000 > file.txt
SAMPLE:
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

or we can create a file consisting of an alphabetic and numeric character:

$ < /dev/urandom tr -dc "[:alnum:]" | head -c1000 > file.txt
SAMPLE:
CCjeuAhJNc4yxBfeMbbYX1U1TnSCVS5oiV53MtGoA6s45FAw9H9PyfZJHrA421



Let’s add some TABs and spaces and new line characters:

$ < /dev/urandom tr -dc "\t\n [:alnum:]" | head -c1000 > file.txt
SAMPLE:
AKelkoPRzlQK9MKO3xzpcfpnbnxNqkBlyn0YfsDZne1 V iZRU5J
iKuahZjmeEeTutFQH4ex7UdMmVxxRrqDmiMosdeTmu	g0sjFIZb
Jox0IXZZGZ2 WSG7pYjpop5AB1gUGAcoJxuTlX

In the last example we will create a random text file of 1000000000 bytes containing any characters, tabs and new lines:

$ < /dev/urandom tr -dc "[:space:][:print:]" | head -c1000000000 > file
SAMPLE:
*)d
   qTND;k$=2h#eSY[Cu
l1w:M,|.&x}Jzla<rS.=@<Xmd9;Fc

@PPD'$I4j?OBk yOP|tEGjr`?B~IT
8pgr$Tpj3mj6v
             $?:OZw.%h`7s7G4iXDN

Here is how the file looks under the od microscope:

$ od -a file
0000000   *   )   d  vt   q   T   N   D   ;   k   $   =   2   h   #   e
0000020   S   Y   [   C   u  nl   m   n   6   .   y   I   |   .   &   x
0000040   }   J   z   l   a   <   r   S   .   =   @   <   X   m   d   9
0000060   ;   F   c  cr   l   1   w   :   M   ,  nl  vt   @   P   P   D
0000100   '   $   I   4   j   ?   O   B   k  sp   y   O   P   |   t   E
0000120   G   j   r   `   ?   B   ~   I   T  nl   8   p   g   r   $   T
0000140   p   j   3   m   j   6   v  vt   $   ?   :   O   Z   w   .   %
0000160   h   `   7   s   7   G   4   i   X   D   N  ff   0   d   h   g
0000200   *   N   u   &   (   9   u   (   v   I   n   T   -   J   z   ;
0000220   2   v   U   L   :   s   X   a   {   )   s   W   U   s   H   5
0000240   b   D   >   9   Q  sp   #   &   q   w   H   S   [   C   {  vt
0000260  sp  cr   H   (   N   ;   5   <   g   $  ht   0  nl   @   5   O


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