How to iterate through multiple directories with multiple ifs in bash? - bash

Question

unfortunately I'm quite new at bash, and I want to write a script that will start in a main directory, and check all subdirectories one by one for the presence of certain files, and if those files are present, perform an operation on them. For now, I have written a simplified version to test whether I can do the first part (checking for the files in each directory). This code runs without any errors that I can tell, but it does not echo anything to say that it has successfully found the files which I know are there.
#!/bin/bash
runlist=(1 2 3 4 5 6 7 8 9)
for f in *; do
if [[ -d {$f} ]]; then
#if f is a directory then cd into it
cd "{$f}"
for b in $runlist; do
if [[ -e "{$b}.png" ]]; then
echo "Found {$b}"
#if the file exists then say so
fi
done
cd -
fi
done
'''

Answer 1

Welcome to stackoverflow.
The following will do the trick (a combination of find, array, and if then else):
# list of files we are looking for
runlist=(1 2 4 8 16 32 64 128)
#find each of above anywhere below current directory
# using -maxdepth 1 because, based on on your exam you want to look one level only
# if that's not what you want then take out -maxdepth 1 from the find command
for b in ${runlist[#]}; do
echo
PATH_TO_FOUND_FILE=`find . -name $b.png`
if [ -z "$PATH_TO_FOUND_FILE" ]
then
echo "nothing found" >> /dev/null
else
# You wanted a postive confirmation, so
echo found $b.png
# Now do something with the found file. Let's say ls -l: change that to whatever
ls -l $PATH_TO_FOUND_FILE
fi
done
Here is an example run:
mamuns-mac:stack foo$ ls -lR
total 8
drwxr-xr-x 4 foo 1951595366 128 Apr 11 18:03 dir1
drwxr-xr-x 3 foo 1951595366 96 Apr 11 18:03 dir2
-rwxr--r-- 1 foo 1951595366 652 Apr 11 18:15 find_file_and_do_something.sh
./dir1:
total 0
-rw-r--r-- 1 foo 1951595366 0 Apr 11 17:58 1.png
-rw-r--r-- 1 foo 1951595366 0 Apr 11 17:58 8.png
./dir2:
total 0
-rw-r--r-- 1 foo 1951595366 0 Apr 11 18:03 64.png
mamuns-mac:stack foo$ ./find_file_and_do_something.sh
found 1.png
-rw-r--r-- 1 foo 1951595366 0 Apr 11 17:58 ./dir1/1.png
found 8.png
-rw-r--r-- 1 foo 1951595366 0 Apr 11 17:58 ./dir1/8.png
found 64.png
-rw-r--r-- 1 foo 1951595366 0 Apr 11 18:03 ./dir2/64.png