why does noone inprove bash such that you can write a normal foor loop with whitespace in file names?
I know that there are ten different alternatives. Why don't we simply improve the basic stuff?
You can already write a for loop that handles whitespace in file names, just use quotes around the file name variable:
"whitespace in file names", please don't.
@TigrisMorte Why not? I don't understand the hate with using valid filename characters in filenames. If anything I would argue it makes detecting non-conformant code easier... you wouldn't want a program to skip processing a file because it has the letter Z in it would you?
Makes CLI involving the space a pain. Use an underscore if you must have a visual space, but best practices would be to use Camel Case, no punctuation (including spaces), and include the date in Gregorian format CCYYMMDD
I don't know if any given system shall issues or could handle it fine, but I know some systems cannot handle spaces in file names. There is no reason to tempt fate.
Am I not reading your question right? Just quote the variable and filenames with spaces work fine.
for i in *; do
cat "$i" ;
done
As others have said, if you quote your variables, they won't get split on spaces. The Unix shell unfortunately has ton of gotchas like this, and the reason this is not changed is backwards-compatibility. Lots of shell scripts depend on this behavior, e.g. there might be something like:
flags="-a -l"
ls $flags
If you quote this (ls "$flags"), ls will see it as one argument, instead of splitting it into two arguments. You could patch the shell to not split arguments by default, and invent some other syntax for when you want this splitting behavior, but that would break a ton of existing shell scripts, and confuse users who are already familiar with the way it works right now. It would also make the shell incompatible with other shells, and violate the POSIX standard.
The reason for this is not backwards compatibility, the reason is that it would be stupid. Space appears a lot more often in situations where you need a separator than in filenames so why would you make the common case harder to use to save some typing in the edge case?
I disagree. The vast majority of the time when writing shell scripts, I quote variables, because that's almost always what I want. Splitting is basically only useful if you have a list of arguments, and you know for sure there are no spaces in any of the arguments (so no filenames).
(The workarounds in pure POSIX shell are btw super annoying if you want to pass a list arguments that may have spaces in them: You can abuse the special "$@" variable. Or you could probably also construct something with xargs.)
@barbara Is bash itself not already an improvement on ""the basic stuff""?
...and whitespace in filenames is simply unacceptable, and should not be encouraged. 😆
What's wrong with the method we've been usin forever of working with dumbly named files? Just "enclose em", or use\ an\ escape\ char in em.
Why don't we improve the basic stuff, like processor architecture?
Because if we do, we make everything we have working now break. So everything would need be ported to this new architecture.
The same with bash or any other foundation lib.
And also these "improvements" may make these libs more complex and, therefore, more unstable and hackable.
The simple is simple for a reason: It works trustfully
That's quite a lot of comments so far with nobody saying
IFS='
'
@kbal Don't you mean IFS=$'\\n' ?
Sure, or IFS=echo "\n" if you like
i have bad news: bash is already a massively improved/extended ksh clone. ksh was a massively improved/extended sh clone. sh got a ton of improvements early on.
this is about as good as you can get without breaking compatibility completely (bash already breaks compatibility with posix sh in some ways).
anyway, once you've figured out the hermetic incantations required to work with filenames with whitespace in them, it'll be time to write scripts that can handle filenames with newlines in them :D
Most shells will issue $PS2 as the continuation prompt if you quote a filename and try to insert a carriage return.
Ctrl-V Ctrl-J is the explicit keypress pair to insert a carriage return without triggering $PS2, but beware: If the carriage return is outside of quotes, that's equivalent to starting a new command in much the same way a semicolon or a new line in a shell script would.
echo "hello^V^Jthere" [Enter] echoes hello on one line and then there on the next, but echo hello^V^Jthere [Enter] will echo hello then try to run a command called there
We'd have to assume that whatever fixes spaces in filenames would also have an option to fix this subtlety. And I say to whoever tries: Good luck with that.
You tell us; you haven't improved the basic stuff so you have the answer already in your own behaviour.
Probably backwards compatibility with existing scripts.
It has nothing to do with bash specifically - other shells like sh, csh, tcsh, zsh, etc. are the same. Whitespace in UNIX is just that way by design. And it's been a long while since I used a Windows CLI but they were that way too - plus added all that weirdness about ~1 at the ends of filenames, and Mac OSX also. So not even just UNIX, but it's how the CLIs tend to work, where whitespace acts as the "delimiter" between arguments sent to a program.
program_name arg1 arg2 arg3 arg4
So if you use whitespace like "cp file 1 file 2", the CLI sends arg1="file", arg2="1", arg3="file", arg4="2", rather than arg1="file 1" and arg2="file 2". These are just the foundational rules of how CLIs work - a computer can't read your mind, and this is how you precisely tell it what you want, within this highly rigid framework to avoid misunderstandings.
The alternative is to use a GUI, so like see file, drag file, and ofc that has its own set of tradeoffs good and bad.
Yeah, for this reason, lots of full-fledged programming languages actually make you specify the arguments as a list of strings directly, so for example:
Command::new("cp") .args(["file 1", "file 2”])It's a subset of the standard delimiter problem: if I want to use the delimiter inside of an entry, can I even do that and if so then how?
e.g. in comma-delimited lists you could "escape" the commas individually, or encapsulate each entry inside quotes, or provide each entry by name, etc. - all of which significantly complicates the retrieval process by adding greater complexity to decide on rules determining how it all works (like if by name, then what if the user [stupidly? on purpose?] provides multiple entries with the same name - do subsequent ones overwrite the earlier ones or their contents get appended to the end and if the latter, is any separation provided between them? and on and on it goes):
Common English has issues with this too like is a list with "John, Marsha, Barbie and Ken" 4 entries or just 3 where the latter is a pairing? (leading to Oxford comma discussion:-P it is very important though bc while while individual people may have similar needs like food, pairings may have different constraints like if they drive together then they need less parking space)
So this delimiter issue is not even specific to CLIs, nor even computers in general - it is a universal problem with any communication system.
Zsh has some important differences in how it handles whitespace and quoting, which affects OP's exact example.
Consider this:
touch a b c 'd e f' 'g h i' for f in *; do ls -la $f; doneIn zsh, this works. In bash, it will give you six errors saying d, e, f, g, h, and i do not exist.
touch a b c 'd e f' 'g h i' for f in *; do ls -la "$f"; donefxd
That only affects whitespaces within quotes though. Still, fair point, except I just tried a bunch of stuff in both bash and zsh and touching a file works, echoing a string works, then I stopped so I don't know about the asterisk but we have already veered far away from what OP said: "normal foor (sic) loop with whitespace in file names" - whereas what you had seems significantly more advanced than a "normal" foor (sic:-P) loop.
Notably, Mac OSX right out of the box uses zsh. I haven't touched "standard" personal distros for a number of years but a quick search suggests that Mint, Ubuntu, and NixOS all use bash by default - which halfway though not entirely surprises me? Anyway if OP wants to change their default shell to something more advanced, that would be fine for common every-day usage, though asking for bash itself to now be changed after decades of backwards compatibility seems a non-starter to me. There are reasons for why it works as it does, and those reasons have nothing to do with it being "old", but rather b/c it "works".
And the underlying reason for that is b/c we are still using keyboards. The addition of mice as HUDs enabled drag-and-drop, and perhaps some kind of glove or fingertip reader or eyesight-tracker may allow the same, like Minority Report (an old movie) or Iron Man style pinching an "object", grabbing it and letting it go, is basically just another style of "mouse". Afaik, there hasn't been even a hint of anything truly revolutionary for all this time. Although I can envision one such idea: combining keyboard+"mouse" in a more intelligent way, like if you start typing a command, then fix your eyes on the screen to a particular file and perhaps flick your eyes in a particular direction to indicate acceptance and it could fill it in for you, without having to move your hands away from the keyboard. With glasses and ubiquitous cameras everywhere now, we might see something like that in a few decades? Though it would put further pressure onto privacy concerns over having a camera watching every move you make.