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About bash : How-to-go-to-each-directory-and-execute-a-command

Question Detail

How do I write a bash script that goes through each directory inside a parent_directory and executes a command in each directory.

The directory structure is as follows:

parent_directory (name could be anything – doesnt follow a pattern)

  • 001 (directory names follow this pattern)
    • 0001.txt (filenames follow this pattern)
    • 0002.txt
    • 0003.txt
  • 002
    • 0001.txt
    • 0002.txt
    • 0003.txt
    • 0004.txt
  • 003
    • 0001.txt

the number of directories is unknown.

Question Answer

This answer posted by Todd helped me.

find . -maxdepth 1 -type d \( ! -name . \) -exec bash -c "cd '{}' && pwd" \;

The \( ! -name . \) avoids executing the command in current directory.

You can do the following, when your current directory is parent_directory:

for d in [0-9][0-9][0-9]
do
    ( cd "$d" && your-command-here )
done

The ( and ) create a subshell, so the current directory isn’t changed in the main script.

If you’re using GNU find, you can try -execdir parameter, e.g.:

find . -type d -execdir realpath "{}" ';'

or (as per @gniourf_gniourf comment):

find . -type d -execdir sh -c 'printf "%s/%s\n" "$PWD" "$0"' {} \;

Note: You can use ${0#./} instead of $0 to fix ./ in the front.

or more practical example:

find . -name .git -type d -execdir git pull -v ';'

If you want to include the current directory, it’s even simpler by using -exec:

find . -type d -exec sh -c 'cd -P -- "{}" && pwd -P' \;

or using xargs:

find . -type d -print0 | xargs -0 -L1 sh -c 'cd "$0" && pwd && echo Do stuff'

Or similar example suggested by @gniourf_gniourf:

find . -type d -print0 | while IFS= read -r -d '' file; do
# ...
done

The above examples support directories with spaces in their name.


Or by assigning into bash array:

dirs=($(find . -type d))
for dir in "${dirs[@]}"; do
  cd "$dir"
  echo $PWD
done

Change . to your specific folder name. If you don’t need to run recursively, you can use: dirs=(*) instead. The above example doesn’t support directories with spaces in the name.

So as @gniourf_gniourf suggested, the only proper way to put the output of find in an array without using an explicit loop will be available in Bash 4.4 with:

mapfile -t -d '' dirs < <(find . -type d -print0)

Or not a recommended way (which involves parsing of ls):

ls -d */ | awk '{print $NF}' | xargs -n1 sh -c 'cd $0 && pwd && echo Do stuff'

The above example would ignore the current dir (as requested by OP), but it’ll break on names with the spaces.

See also:

  • Bash: for each directory at SO
  • How to enter every directory in current path and execute script? at SE Ubuntu

You can achieve this by piping and then using xargs. The catch is you need to use the -I flag which will replace the substring in your bash command with the substring passed by each of the xargs.

ls -d */ | xargs -I {} bash -c "cd '{}' && pwd"

You may want to replace pwd with whatever command you want to execute in each directory.

If the toplevel folder is known you can just write something like this:

for dir in `ls $YOUR_TOP_LEVEL_FOLDER`;
do
    for subdir in `ls $YOUR_TOP_LEVEL_FOLDER/$dir`;
    do
      $(PLAY AS MUCH AS YOU WANT);
    done
done

On the $(PLAY AS MUCH AS YOU WANT); you can put as much code as you want.

Note that I didn’t “cd” on any directory.

Cheers,

for dir in PARENT/*
do
  test -d "$dir" || continue
  # Do something with $dir...
done

While one liners are good for quick and dirty usage, I prefer below more verbose version for writing scripts. This is the template I use which takes care of many edge cases and allows you to write more complex code to execute on a folder. You can write your bash code in the function dir_command. Below, dir_coomand implements tagging each repository in git as an example. Rest of the script calls dir_command for each folder in directory. The example of iterating through only given set of folder is also include.

#!/bin/bash

#Use set -x if you want to echo each command while getting executed
#set -x

#Save current directory so we can restore it later
cur=$PWD
#Save command line arguments so functions can access it
args=("[email protected]")

#Put your code in this function
#To access command line arguments use syntax ${args[1]} etc
function dir_command {
    #This example command implements doing git status for folder
    cd $1
    echo "$(tput setaf 2)$1$(tput sgr 0)"
    git tag -a ${args[0]} -m "${args[1]}"
    git push --tags
    cd ..
}

#This loop will go to each immediate child and execute dir_command
find . -maxdepth 1 -type d \( ! -name . \) | while read dir; do
   dir_command "$dir/"
done

#This example loop only loops through give set of folders    
declare -a dirs=("dir1" "dir2" "dir3")
for dir in "${dirs[@]}"; do
    dir_command "$dir/"
done

#Restore the folder
cd "$cur"

I don’t get the point with the formating of the file, since you only want to iterate through folders… Are you looking for something like this?

cd parent
find . -type d | while read d; do
   ls $d/
done

you can use

find .

to search all files/dirs in the current directory recurive

Than you can pipe the output the xargs command like so

find . | xargs 'command here'

  #!/bin.bash
for folder_to_go in $(find . -mindepth 1 -maxdepth 1 -type d \( -name "*" \) ) ; 
                                    # you can add pattern insted of * , here it goes to any folder 
                                    #-mindepth / maxdepth 1 means one folder depth   
do
cd $folder_to_go
  echo $folder_to_go "########################################## "
  
  whatever you want to do is here

cd ../ # if maxdepth/mindepath = 2,  cd ../../
done

#you can try adding many internal for loops with many patterns, this will sneak anywhere you want

You could run sequence of commands in each folder in 1 line like:

for d in PARENT_FOLDER/*; do (cd "$d" && tar -cvzf $d.tar.gz *.*)); done

for p in [0-9][0-9][0-9];do
    (
        cd $p
        for f in [0-9][0-9][0-9][0-9]*.txt;do
            ls $f; # Your operands
        done
    )
done

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