shell script to create empty files with all possible permissions-CodePudding

How to write a shell script that creates empty files with all possible permissions. File names should be, for example, rwxrw_r__.txt. I know how to do it manually. As an example:

#!/bin/bash

touch task5/rwxrwxrwx.txt | chmod 777 task5/rwxrwxrwx.txt
touch task5/rwxr-xr-x.txt | chmod 755 task5/rwxr-xr-x.txt
touch task5/rwx------.txt | chmod 700 task5/rwx------.txt
touch task5/rw-rw-rw-.txt | chmod 666 task5/rw-rw-rw-.txt
touch task5/rw-r--r--.txt | chmod 644 task5/rw-r--r--.txt
touch task5/rw-------.txt | chmod 600 task5/rw-------.txt

I do not know how to write a script that will create files according to the required template and give them permissions

CodePudding user response：

Do a loop:

for ((i=0; i < 512; i  )); do 
    mod=$(printf "o\n" "$i"); 
    touch ${mod}.txt; chmod $mod $mod.txt; 
done

Rather than trying to construct the names, if you want the names to look like the output of ls -l, just do something like

for ((i=0; i < 512; i  )); do
    mod=$(printf "o\n" "$i") 
    touch ${mod}.txt
    chmod $mod $mod.txt
    n=$(ls -l $mod.txt | awk '{print $1}')
    mv $mod.txt $n.txt
done

CodePudding user response：

It's just a permutations problem.

p=( --- --x -w- -wx r-- r-x rw- rwx ) # the set of permissions 
for u in "${p[@]}"; do for g in "${p[@]}"; do for o in "${p[@]}"; do
  f="task5/$u$g$o.txt"; touch -- "$f" && chmod "u=$u,g=$g,o=$o" -- "$f" 
done; done; done

This took a little over a minute on my laptop.