I am surprised that there still is no built in way to pipe stdout and stderr. *| would be much more ergonomic than 2>&1 |.
Doesn't |& work with bash?
&>
What does " 2>&1 " mean?
91–100 of 260 posts
Re: What does " 2>&1 " mean?
#92I find it easier to understand in terms of the Unix syscall API. `2>&1` literally translates as `dup2(1, 2)`, and indeed that's exactly how it works. In the classic unix shells that's all that happens; in more modern shells there may be some additional internal bookkeeping to remember state. Understanding it as dup2 means it's easier to understand how successive redirections work, though you also have to know that re…
I find it very intuitive as is
Re: What does " 2>&1 " mean?
#93Earlier quoted context omitted.
Yes. There are many reasons why one shouldn't use sh/bash for scripting. But my main reason is that most scripts break when you call them with filenames that contain spaces. And they break spectacularly.
You're not wrong, but there's fairly easy ways to deal with filenames containing spaces - usually just enclosing any variable use within double quotes will be sufficient. It's tricker to deal with filenames that contain things such as line breaks as that usually involves using null terminated filenames (null being the only character that is not allowed in filenames). e.g find . -type f -print0
You're not wrong, but at my place, our main repository does not permit cloning into a directory with spaces in it.
Three factors conspire to make a bug:
1. Someone decides to use a space
2. We use Python
3. macOS
#!/usr/bin/env python3
Since we use Python virtualenvs,
#!/home/bob/src/repo/.venv/bin/python3
#!/home/bob/src/repo with a space/.venv/bin/python3
As I also discovered when I discovered this, the Python tooling checks for this! It will instead emit a polyglot!
#!/bin/bash
#
# the bash will find the right Python interpreter, and then re-exec this
# script using that interpreter. The Python will skip the bash portion,
# b/c of cleverness in the polyglot.
Took me forever to figure out what was going on. So yeah … spaces in paths. Can't recommend them. Stuff breaks, and it breaks in weird and hard to debug ways.
Re: What does " 2>&1 " mean?
#94Man I miss stack overflow. It feels so much better to ask humans a question then the machine, but it feels impossible to put the lid back on the box.
and no ai fluff to start or end the answer, just facts straight to the point.
Re: What does " 2>&1 " mean?
#95The comments on stackoverflow say the words out of my mouth so I'll just copy & paste here:
> but then shouldn't it rather be &2>&1?
> & is only interpreted to mean "file descriptor" in the context of redirections. Writing command &2>& is parsed as command & and 2>&1
That's where all the confusion comes from. I believe most people can intuitively understand > is redirection, but the asymmetrical use of & throws them off.
Interestingly, Powershell also uses 2>&1. Given an once-a-lifetime chance to redesign shell, out of all the Unix relics, they chose to keep (borrow) this.
Re: What does " 2>&1 " mean?
#96Awesome. Next week I will forget it again.
Re: What does " 2>&1 " mean?
#97Somewhat off topic, but related: I worked at this place that made internet security software. It ran on Windows, and on various flavors of Unix.
One customer complained about our software corrupting files on their hard disk. Turns out they had modified their systems so that a newly-spawned program was not given a stderr. That is, it was not handed 0, 1, and 2 (file descriptors), but only 0 and 1. So whenever our program wrote something to stderr, it wrote to whatever file had been the first one opened by the program.
We talked about fixing this, briefly. Instead we decided to tell the customer to fix their broken environment.
Re: What does " 2>&1 " mean?
#98Earlier quoted context omitted.
It should be a lesson to learn on how simple, logical and reliable tools can last decades.
Bash syntax is anything but simple or logical. Just look at the insane if-statement syntax. Or how the choice of quotes fundamentally changes behavior. Argument parsing, looping, the list goes on.
if statements are pretty simple
if $command; then else fi
You may be complaining about the syntax for the test command specifically or bash’s [[ builtin
Also the choice of quotes changing behavior is a thing in:
1. JavaScript/typescript 2. Python 3. C/C++ 4. Rust
In some cases it’s the same difference, eg: string interpolation in JavaScript with backticks
Re: What does " 2>&1 " mean?
#99Earlier quoted context omitted.
You're not wrong, but there's fairly easy ways to deal with filenames containing spaces - usually just enclosing any variable use within double quotes will be sufficient. It's tricker to deal with filenames that contain things such as line breaks as that usually involves using null terminated filenames (null being the only character that is not allowed in filenames). e.g find . -type f -print0
You're not wrong, but at my place, our main repository does not permit cloning into a directory with spaces in it. Three factors conspire to make a bug: 1. Someone decides to use a space 2. We use Python 3. macOS Say you clone into a directory with a space in it. We use Python, so thus our scripts are scripts in the Unix sense. (So, Python here is replacable with any scripting language that uses a shebang, so long as…
If all of your scripts run in the same venv (for a given user), can you inject that into the PATH and rely on env just finding the right interpreter?
I suppose it would also need env to be able to handle paths that have spaces in them.
Re: What does " 2>&1 " mean?
#100Earlier quoted context omitted.
Bash syntax is anything but simple or logical. Just look at the insane if-statement syntax. Or how the choice of quotes fundamentally changes behavior. Argument parsing, looping, the list goes on.
if statements are pretty simple if $command; then else fi You may be complaining about the syntax for the test command specifically or bash’s [[ builtin Also the choice of quotes changing behavior is a thing in: 1. JavaScript/typescript 2. Python 3. C/C++ 4. Rust In some cases it’s the same difference, eg: string interpolation in JavaScript with backticks
> Also the choice of quotes changing behavior is a thing in:
In those languages they change what's contained in the string. Not how many strings you get. Or what the strings from that string look like. ($@ being an extreme example)