Dealing with Spaces in Filenames
Just grabbed a copy of the magazine from the bookstore but it was still the February edition. I am responding to callout at the end of the "Working the Shell" article on "Dealing with Spaces in Filenames" by Dave Taylor. This is my first time on the forum and I couldn't find an existing thread on this so I'm starting this one. Sorry if this is the wrong place to do this.
I'm a little unclear about some things Dave says on IFS. At one point, he quotes the Bash man page's IFS entry under the Shell Variables heading and then goes on to say that this doesn't really solve our filename problem. Later in the article he includes IFS in his possible solution paths. I'm not really sure if this is contradictory here or if I'm missing something.
As it happens, I do actually use IFS for exactly this purpose. The Bash man page is in dire need of an update. This is unfortunate because IFS is used in other areas of the Bash shell. This entry in the man page should reflect that broader scope. Actually, if you search the man page for IFS, you'll see many hits, notably under the Expansion > Word Splitting heading.
Here is how I use IFS for this purpose:
#!/bin/sh FILENAMES=$(ls) OIFS="$IFS" IFS=$'\n' for x in $FILENAMES do echo "$x" done IFS="$OIFS"
By setting IFS in this way, we are removing the space and tab portions of its definition. Now we are getting exactly what we want which is separation, or word splitting, on newline characters only.
It's important to note that a lot of people believe 'unset IFS' will revert revert IFS back to the default value. This is actually not true. This will really just set IFS to null. According to the man page, (which is accurate this time) when IFS is set to null and is used by a builtin it is assumed to be a space. This is in contrast to the default value of "\s\t\n". By creating and setting OIFS to equal IFS (the double quotes here are required to make this work correctly!) we can restore it to the original value later.
Is this what Dave was looking for?
P.S. The example script above will also handle the quoted filenames from the article.
Practical books for the most technical people on the planet. Newly available books include:
- Agile Product Development by Ted Schmidt
- Improve Business Processes with an Enterprise Job Scheduler by Mike Diehl
- Finding Your Way: Mapping Your Network to Improve Manageability by Bill Childers
- DIY Commerce Site by Reven Lerner
Plus many more.
- Unikernels, Docker, and Why You Should Care
- Controversy at the Linux Foundation
- diff -u: What's New in Kernel Development
- Non-Linux FOSS: Snk
- 22 Years of Linux Journal on One DVD - Now Available
- Wine 1.8 Released
- Don't Burn Your Android Yet
- Giving Silos Their Due
- What's New in 3D Printing, Part III: the Software