Generating Random Text Data in Bash with Variable Size

This article introduces how to generate random text data of n characters wide by n characters tall from the Bash command line on Linux computers and servers.

An example of generating text data composed of random characters, 5 characters x 5 characters, totaling 25 characters:

yuis ASUS /mnt/c/pg$ gentext 5 5 random
AsVDT
iCPZi
Ihlv8
NVwc0
TofvP

If random numbers are not needed, specify the third argument as blank or any character to output text data with the same character.

yuis ASUS /mnt/c/pg$ gentext 5 5
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX

If you want to output the generated data to a file, pipe it as usual.

yuis ASUS /mnt/c/pg$ gentext 5 5 random > tmp.txt

Code

Here’s the code:

gentext02(){
  : <<< '
  generate a large size of text contents.

  e.g. gentext02 [width] [height] [char]
  e.g. gentext02 100 100 Z
  e.g. gentext02 100 100 random > tmp.txt

  i.e. check how long time fzf takes against to a large of text contents.
    tmpdird
    push gentext02 20 50000 random > tmp.txt
    cat tmp.txt | fzf
  '

  for i in $(seq "${2:-10}") ; do
    # printf "${3:-X}%.0s" {1..${1:-10}} ; printf '\n'

      [[ "${3}" =~ rand|random ]] && {
        # printf "$( randsel {a..z} )%.0s" $( eval "echo {1..${1:-10}}" ) ; printf '\n'
        random ${1:-10}
      } || {
        printf "${3:-X}%.0s" $( eval "echo {1..${1:-10}}" ) ; printf '\n'
      }

  done

}

alias gentext="gentext02"

Code Explanation

The gentext function generates text data of n characters wide by n characters tall.

for i in $(seq "${2:-10}") ; do

[[ "${3}" =~ rand|random ]] && {
  random ${1:-10}
} || {
  printf

"${3:-X}%.0s" $( eval "echo {1..${1:-10}}" ) ; printf '\n'
}

random ${1:-10}

printf "${3:-X}%.0s" $( eval "echo {1..${1:-10}}" ) ; printf '\n'

printf "${3:-X}%.0s" $( eval "echo {1..${1:-10}}" ) ; printf '\n'

alias gentext="gentext02"

Usage

Add this to ~/.bashrc or similar, then restart the shell or load it with source ~/.bashrc or similar.

Using the gentext command, you can generate text data of n characters wide by n characters tall.

random(){
  ARG1=${1:-32}
  # cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w $1 | head -n 1
  cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w $ARG1 | head -n 1
}