Shell Programming and Scripting

#!/bin/bash
 log_file="/etc/file1.log"
 LIST="a A b B c C d D e E f F g G h H i I j J k K l L m M n N o O p P q Q r R s S t T u U v V w W x X y Y z Z 0 1 2 3 4 5 6 7 8 9 ! £ $ % ^ & ( ) , . / ; ' # [ ] { } : @ ~ < > ?"
for a in $LIST
 do
        for b in $LIST
        do
                for c in $LIST
                do
                        for d in $LIST
                        do
                                for e in $LIST
                                do
                                        for f in $LIST
                                        do
                                                for g in $LIST
                                                do
                                                        for h in $LIST
                                                        do
                                                                for i in $LIST
                                                                do
                                                                        for j in $LIST
                                                                        do
                                                                                for k in $LIST
                                                                                do
                                                                                        for l in $LIST
                                                                                        do
                                                                                                for m in $LIST
                                                                                                do
                                                                                                echo -n " $a$b$c$d$e$f$g$h$i$j$k$l$m " >> $log_file
                                                                                                echo -n " $a$b$c$d$e$f$g$h$i$j$k$l$m "
                                                                                                done
                                                                                        done
                                                                                done
                                                                        done
                                                                done
                                                        done
                                                done
                                        done
                                done
                        done
                done
        done
 done

#!/bin/bash

LIST=(0 1 2 3 4 5 6 7 8 9)
INDEX=(0 0 0)

while [ ${INDEX[0]} -lt ${#LIST[@]} ]
do
        echo "${INDEX[@]}"

        I=$(( ${#INDEX[@]} - 1 )) # Which digit are we adding to

        ((INDEX[$I]++))

        # Carry 2 10 into 3 0
        while [ $I -gt 0 ] && [ ${INDEX[$I]} -ge ${#LIST[@]} ]
        do
                ((INDEX[$I] -= 10))     # Subtract ten from current digit
                ((I--))                 # Go back one digit
                ((INDEX[$I] ++ ))       # Carry one
        done
done

#!/bin/bash
log_file="./file1.log"
LIST="a A b B c C d D e E f F g G h H i I j J k K l L m M n N o O p P q Q r R s S t T u U v V w W x X y Y z Z 0 1 2 3 4 5 6 7 8 9 ! £ $ % ^ & ( ) , . / ; ' # [ ] { } : @ ~ < > ?"
# disable globbing; needed because of the unquoted $LIST that contains special characters like "?"
set -f

# the number of digits
depth=26

do_digit(){
if [[ $((depth)) -eq 0 ]]
then
  printf "%s\n" "$1"
  printf "%s\n" "$1" >&3
  return
fi
((depth-=1))
local i
for i in $LIST
do
  do_digit "$1$i"
done
((depth+=1))
}

# open $log_file once with descriptor 3
# writes to &3 will go there
do_digit 3>"$log_file"

sudo head -n NUMBER FILE > FILE
sudo shuf FILE -o FILE