Capturing output of find . -print0 into a bash array

Question

Using find . -print0 seems to be the only safe way of obtaining a list of files in bash due to the possibility of filenames containing spaces, newlines, quotation marks etc.

However, I'm having a hard time actually making find's output useful within bash or with other command line utilities. The only way I have managed to make use of the output is by piping it to perl, and changing perl's IFS to null:

find . -print0 | perl -e '$/="\0"; @files=<>; print $#files;' 

This example prints the number of files found, avoiding the danger of newlines in filenames corrupting the count, as would occur with:

find . | wc -l 

As most command line programs do not support null-delimited input, I figure the best thing would be to capture the output of find . -print0 in a bash array, like I have done in the perl snippet above, and then continue with the task, whatever it may be.

How can I do this?

This doesn't work:

find . -print0 | ( IFS=$'\0' ; array=( $( cat ) ) ; echo ${#array[@]} ) 

A much more general question might be: How can I do useful things with lists of files in bash?

Answer 1

Shamelessly stolen from Greg's BashFAQ:

unset a i while IFS= read -r -d $'\0' file; do     a[i++]="$file"        # or however you want to process each file done < <(find /tmp -type f -print0) 

Note that the redirection construct used here (cmd1 < <(cmd2)) is similar to, but not quite the same as the more usual pipeline (cmd2 | cmd1) -- if the commands are shell builtins (e.g. while), the pipeline version executes them in subshells, and any variables they set (e.g. the array a) are lost when they exit. cmd1 < <(cmd2) only runs cmd2 in a subshell, so the array lives past its construction. Warning: this form of redirection is only available in bash, not even bash in sh-emulation mode; you must start your script with #!/bin/bash.

Also, because the file processing step (in this case, just a[i++]="$file", but you might want to do something fancier directly in the loop) has its input redirected, it cannot use any commands that might read from stdin. To avoid this limitation, I tend to use:

unset a i while IFS= read -r -u3 -d $'\0' file; do     a[i++]="$file"        # or however you want to process each file done 3< <(find /tmp -type f -print0) 

...which passes the file list via unit 3, rather than stdin.