testFilesMake is a Linux portable executable created from the bash script Test_Files_Make (private Github repository) using shc.

Use testFilesCreate as an alternative :

• If a tree of directories is required for test data;
• If random sized data files are required. Size range is user defined
• If all files created have to be identical.
• If you do not require sparse files. Sparse files only avalaible in testFilesMake

This requires a Linux bash environment to run. Will run in Microsoft WSL2(Linux), TestFilesMake will not run in MSYS2, Gitbash and Cygwin environmants. testFilesMake is an exceutable created from the shc utility. More : Github shc

File Contents

• Each file is filled with its own set of ramdom data, no files are copied.
• Binary (default) from /dev/urandom. (Not compressible)
• -P any printable characters from the ASCI set. Optional
• -D Only the 0 to 9 digits. Optioal
• -S Sparse file nulls. Only to be used in Linux, Unix and WSL2. The sparse file option is NOT to be used on MS Windows filesystems and WSL1, MSYS2, Gitbash and Cygwin - see below

Other Options

-f <file size> Manditory, minimum 1 byte. File sizes have to be designated by B, K, M or G. Example 2KiB = 2K, 3MiB = 3M 200GiB = 200G

-o <exisiting directory> Optional, create file in a exisiting directory. Default is your current directory.

Files created will have names in the format of tfm_YYYYMMDD-mmss_file_<file number>

File Contents: Digits

-D n Where n is a number 1 to 10.

This selects the numbers in the character pool used

• n=1 files will be filled with the character zero '0'
• n=2 files will be filled with 0 and 1
• n=3 files will be filled with 0,1 and 2
• n=7 files will be filled with 0 and numbers 1 to 6
• n=10 files will be filled with a randon numbers of 0 to 9

File Contents: Printable ASCI characters:_

-P n Where n is a number 1 to 95.(the ASCI character set)

• n=1 file will filled with repeats of the character 'A'
• n>=2 or n<=26 all characters will be from the lower-case Latin alphabet
• n>=27 characters will be from the 95 printable character set.

Examples:

• n = 10 will select all characters stating at "a" to "j"
• n = 4 will select all characters "a" to "d"
• n = 60 will select all characters from "!" to "\"
• n = 46 will select all characters from "!" to "M"

File Contents: Sparse File

-S Null filled sparse files. Although disk usage is minimal their apparent size may be used to determine capacity usage. Not to be used on Windows filesystems.

VALIDATE FILE CONTENTS

Validate all Files:

    od -N <bytes> -Ax -t x1z <file name>

• Where <bytes> is the number to check from beginning of file.
• Non-printable characters will appear as "dots"
• For sparse files omit <bytes> as it not required.

Validate printable character distribution:

    od -a <file name>  | cut -b 9- | tr " " \\n | egrep -v "^$" | sort | uniq -c

Output

• Column 1 : Character count
• Column 2 : Character being counted. This column should only contain a single charcter, if not then file contents is binary data.

Validate sparse fILes:

• ls -lsh Shows disk usage at start of output, apparent size is in its usual place.
• du -b Shows disk usage in bytes.
• du -b --apparent-size Shows the size the user sees and used filesystem capacity calculations

NOTES

• Binary data may render storage and transmission data dedplication and compression ineffective.
• The smaller range of printable characters used the longer the script runs.
• Testing data duplication, the moost useful range is alphanumeric of 1 to 20 chracters i.e -P 1 to -P 20
• Testing compression, the most useful range is alphanumeric 1 to 40 i.e. -P 1 to -P 40

EXAMPLES

Create ten 5 MiB files containing a randonly distribution of the first 30 printable characters of the ASCII character set.

$./testFilesMake -P 30 -f 5M -n 10
Creating 10x 5M files in /home/ted/tmp/
Files containing random selection from the 30 char set: !"#$%&'()*+,-./0123456789:;<=>

Creating file 1      Done: 5.0M  /home/ted/tmp/tfm_20251019-1916-53_file_1
Creating file 2      Done: 5.0M  /home/ted/tmp//tfm_20251019-1916-53_file_2
Creating file 3      Done: 5.0M  /home/ted/tmp//tfm_20251019-1916-53_file_3
Creating file 4      Done: 5.0M  /home/ted/tmp/tfm_20251019-1916-53_file_4
Creating file 5      Done: 5.0M  /home/ted/tmp/tfm_20251019-1916-53_file_5
Creating file 6      Done: 5.0M  /home/ted/tmp/tfm_20251019-1916-53_file_6
Creating file 7      Done: 5.0M  /home/ted/tmp/tfm_20251019-1916-53_file_7
Creating file 8      Done: 5.0M  /home/ted/tmp/tfm_20251019-1916-53_file_8
Creating file 9      Done: 5.0M  /home/ted/tmp/tfm_20251019-1916-53_file_9
Creating file 10     Done: 5.0M  /home/ted/tmp/tfm_20251019-1916-53_file_10

Total Directory Usage of output directory: /home/ted/tmp
          102435.066 KiB
             100.427 MiB
               0.098 GiB

Total disk usage (du -sk) : 101M

NOTE: Totals are for the entire directory contents not just test files made by this script run
$ 

Create five 1 GiB sparse files

$./testFilesMake -S -f 1G -n 5
Creating 5x 1G SPARSE files in /home/ted/tmp

Creating file 1       DONE: Apparent Size: 1.0G Disk Usage: 0  /home/ted/tmp/tfm_20251019-1937-01_Sfile_1
Creating file 2       DONE: Apparent Size: 1.0G Disk Usage: 0  /home/bob/tmp/tfm_20251019-1937-01_Sfile_2
Creating file 3       DONE: Apparent Size: 1.0G Disk Usage: 0  /home/bob/tmp/tfm_20251019-1937-01_Sfile_3
Creating file 4       DONE: Apparent Size: 1.0G Disk Usage: 0  /home/bob/tmp/tfm_20251019-1937-01_Sfile_4
Creating file 5       DONE: Apparent Size: 1.0G Disk Usage: 0  /home/bob/tmp/tfm_20251019-1937-01_Sfile_5

Total Directory Usage of output directory: /home/ted/tmp
         5242907.188 KiB
            5140.105 MiB
               5.020 GiB

Total disk usage (du -sk) : 32K

NOTE: Totals are for the entire directory contents not just test files made by this script run
$

Create fifty 5GiB files containing only the randonly distributed digits 0, 1 , 2, 3 and 4

testFilesMake -D 5 -f 5G -n 50

Create a single 1MiB file containing these characters randomly distributed !"#$%&'()*+,-./0123456789:;<=>?@ABC

testFilesMake -P 35 -f 1M -n 1

Same as previous, but with files being generated in the test_files directory within the user's home directory.

testFilesMake -P 35 -f 1M -n 1 -o ~/test_files

Create 1,000 1KiB files containing these characters randomly distributed abcdefghij

testFilesMake -P 10 -f 1K -n 1000

WINDOWS SPARSE FILES - How to make:

On Windows run the following as administrator

fsutil File CreateNew  <file name> <size in bytes>
fsutil Sparse SetFlag  <file name>
fsutil Sparse SetRange <file name> 0 <size in bytes>

WSL2-Linux cannot run windows commands and programs that require administrator privilege.