recursion in shell script

Question

I am learning Linux command and I am practicing and trying to write a basic shell script which list all the files and files in subfolders, like ls *, using recursion.

#!/bin/bash

# list-all: one command to list them all!!!!

listit () {
        if [ -d "$1" ]
        then
                listit "$1"
        else
                echo "$1"
        fi  
}

ls | while read items; do
        listit "$items"
done

However, the result shows:

./list-all: line 16:  1101 Done                    ls
      1102 Segmentation fault: 11  | while read items; do
    listit "$items";
done

Is that because shell doesn't allow recursion? please help, thank you!

+1 to you for your learning efforts. Are you aware of ls -R or find . type -f? — glenn jackman
– glenn jackman, Commented May 29, 2013 at 19:26
@glennjackman, Thank you! I just realized you can use these commands. Though for the second one, I think it should be find . -type f — Mike Lee
– Mike Lee, Commented May 31, 2013 at 15:40

kojiro · Accepted Answer · 2013-05-29 17:46:46Z

3

The shell certainly supports recursion. But your function takes arguments, and you're passing it stdin. Besides that, you really shouldn't be parsing the output of ls. Consider this:

listit() {
    while [ "$1" ]; do
        if [ -d "$1" ]; then
            listit "$1"/*
        else
            printf '%s\n' "$1"
        fi
        shift
    done
}

listit *

If you really want to read stdin, you'd have to rewrite listit to do that. That's tricky, since you only get one standard input, and each recursive call would try to own it. Filenames are a simple thing accessible as arguments through globbing, so I'd stick to that.

edited May 29, 2013 at 17:46

answered May 29, 2013 at 16:48

kojiro

77.8k20 gold badges151 silver badges217 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Community · Accepted Answer · 2017-05-23 12:11:20Z

2

You overflowed the stack with an infinite recursion. Consider calling listit /.

The first if will see that / is a directory so it will call listit / which will then call listit / ...

See this answer for what happens next.

edited May 23, 2017 at 12:11

CommunityBot

11 silver badge

answered May 29, 2013 at 16:52

msw

43.7k9 gold badges92 silver badges117 bronze badges

Collectives™ on Stack Overflow

recursion in shell script

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related