Building argument list with an array

Question

I need to build up an argument list for find using values only known at run time. I'm trying to use an array to do so.

Below is a simplified version which uses hard coded values. When I echo out the command it appears to be correct (and when I run it manually it does what I'd expect). When it enters the for-loop it appears to be running find (because I can see the same errors about Permission denied for directories owned by other users as when I run manually). But inside the for-loop, it doesn't echo out any of the .txt files that a manual run finds.

What did I do wrong?

#!/bin/bash

args=(/tmp -iname \"*.txt\")

#args+=(-o -iname \"*.jpg\")

echo command will be: find ${args[@]}
for f in $( find ${args[@]} ); do
    echo found $f
done

The accepted answer below correctly identified the issue. But if I add an additional -iname clause, my script "ignores" all but the last as detailed here:

#!/bin/bash

args=($1)
args+=(-maxdepth $2)
args+=(-iname "*$3")
args+=(-o -iname "*$4")
echo command will be: find "${args[@]}"

find "${args[@]}" -print 2>/dev/null | while read -r f; do
    echo found "$f"
done

For example, when called with /home/me 2 .jpg .png this correctly echoes that the command will be find /home/me -maxdepth 2 -iname *.jpg -o -iname *.png but then my script only echoes the .png files that it finds.

Quote your variables. (e.g. "${args[@]}", "$f", etc.) Also don't read the output of find like that. mywiki.wooledge.org/DontReadLinesWithFor mywiki.wooledge.org/BashFAQ/001 — Etan Reisner
– Etan Reisner, Commented May 18, 2015 at 20:42

Barmar · Accepted Answer · 2015-05-18 21:36:35Z

3

You shouldn't escape the quotes. That will make them literal, so it will try to find files whose names actually begin and end with doublequotes.

args=(/tmp -iname "*.txt")

Then you need to put quotes around ${args[@]} to tell the shell that it should requote them when expanding the array:

find "(" "${args[@]}" ")" -print | while read -r f
do
    echo found "$f"
done

edited May 18, 2015 at 21:36

answered May 18, 2015 at 20:46

Barmar

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4 Comments

user1011471 Over a year ago

Thanks. I ran into another issue and added it to the question instead of sticking it in this comment since it allows for better formatting.

Barmar Over a year ago

When you use -o, you need an action in each branch. I've fixed the answer to put parenthese around everything to group them.

user1011471 Over a year ago

Hm. Actually parens around all the args didn't work for me but parens around just the -iname clauses did. But the other answer that mentioned such parens disappeared...

Barmar Over a year ago

If you have things in $args that need to be distributed among both branches of the -o, then you need additional levels of parentheses. E.g. if you want -maxdepth to apply to both -iname clauses, you need to put them in parentheses.

izabera · Accepted Answer · 2015-05-18 23:57:29Z

1

Bash4 can expand globs recursively with shopt -s globstar.
Just use array=(/tmp/**/*.txt) to get all the elements.

answered May 18, 2015 at 23:57

izabera

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