bash script for $* loop accept command line with spaces in wildcard file names at DuckDuckGo

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bash script for $* loop accept command line with spaces in wildcard file names at DuckDuckGo

Posted by jpluimers on 2026/05/05

Back when I wanted a more universal solution [Wayback/Archive] bash script for $* loop accept command line with spaces in wildcard file names at DuckDuckGo I got into a mess of tips that either did not work at all, or were very convoluted.

As back then I only needed a one-time solution, I just listed the filenames with ls into a text file, did some sed and editing steps, then had each file execute in a separate step. Low tech, non-repeatable when new files appeared, but good enough.

In case I want to go for a more universal solution, below are some links to investigate further. Will likely take me hours, so most of the time this is not worth it. Maybe the subshell plus $IFS (Input Field Separators) is a good start, though it gives me a feeling that in the future it will break something else that was expecting a default $IFS value, as is using while read loop. Both types of solutions feel too convoluted. Same for the array solution below.

I might have just been spoiled with PowerShell piping objects instead of strings having made life so much easier.

Links:

[Wayback/Archive] Passing a string with spaces as a function argument in Bash – Stack Overflow
[Wayback/Archive] How to pass argument with spaces to a shell script function? – Unix & Linux Stack Exchange
[Wayback/Archive] command line – Bash and filenames with spaces – Stack Overflow
Try this:
```
(IFS=$'\n'; grep -li 'regex' $(<listOfFiles.txt))
```
IFS is the Internal Field Separator. Setting it to $'\n' tells Bash to use the newline character to delimit filenames. Its default value is $' \t\n' and can be printed using cat -etv <<<"$IFS".

Enclosing the script in parenthesis starts a subshell so that only commands within the parenthesis are affected by the custom IFS value.
[Wayback/Archive] bash – File names with spaces in scripts – Ask Ubuntu
[Wayback/Archive] bash – Trouble in script with spaces in filename – Unix & Linux Stack Exchange
[Wayback/Archive] find – Making BASH script `for` handle filenames with spaces (or workaround) – Super User
You can make this proof against files with newlines in their names, if you wish, by using a nullbyte delimiter (that being the only character which cannot appear in a *nix filepath):
```
find ... -print0 | while read -d '' -r dir
do
    something with "$dir"
done
```
You will also find using $() instead of backticks to be more versatile and easier. They can be nested much more easily and quoting can be done much more easily. This contrived example will illustrate these points:
```
echo "$(echo "$(echo "hello")")"
```
Try to do that with backticks.
…
See this answer I wrote a few days ago for an example of a script that handles filenames with spaces.

There’s a slightly more convoluted (but more concise) way to achieve what you’re trying to do though:
```
find . -type d -print0 | xargs -0 -I {} mkdir -p ../theredir/{}
```
-print0 tells find to separate the arguments with a null; the -0 to xargs tells it to expect arguments seperated by nulls. This means that it handles spaces fine.

-I {} tells xargs to replace the string {} with the filename. This also implies that only one filename should be used per commandline (xargs will normally stuff as many as will fit on the line)

The rest should be obvious.
[Wayback/Archive] bash – Looping through files with spaces in the names? – Unix & Linux Stack Exchange also fiddles with $IFS
[Wayback/Archive] linux – File names with spaces in BASH – Stack Overflow also goes the $IFS way.
[Wayback/Archive] shell – Bash script error with strings with paths that have spaces and wildcards – Unix & Linux Stack Exchange
Inside quotes, the * will not expand to a list of files. To use such a wildcard successfully, it must be outside of quotes.

Even if the wildcard did expand, the expression "${FILES}" would result in a single string, not a list of files.

One approach that would work would be:
```
#!/bin/bash
DIR="/home/john/my directory/"
for f in "$DIR"/*.txt
do
  echo "${f}"
done
```
In the above, file names with spaces or other difficult characters will be handled correctly.

A more advanced approach could use bash arrays:
```
#!/bin/bash
FILES=("/home/john/my directory/"*.txt)
for f in "${FILES[@]}"
do
  echo "${f}"
done
```
In this case, FILES is an array of file names. The parens surrounding the definition make it an array. Note that the * is outside of quotes. The construct "${FILES[@]}" is a special case: it will expand to a list of strings where each string is one of the file names. File names with spaces or other difficult characters will be handled correctly.

Queries:

--jeroen

This entry was posted on 2026/05/05 at 18:00 and is filed under *nix, *nix-tools, ash/dash, bash, bash, Development, Power User, Scripting, Software Development. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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bash script for $* loop accept command line with spaces in wildcard file names at DuckDuckGo

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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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