4 ms·

Every time I stumble across moreutils, I can’t understand what any of its tool do. Take all these for instance: pee: tee standard input to pipes sponge: soak

by thiht 5y ago

Every time I stumble across moreutils, I can’t understand what any of its tool do. Take all these for instance: pee: tee standard input to pipes sponge: soak up standard input and write to a file ts: timestamp standard input vidir: edit a directory in your text editor vipe: insert a text editor into a pipe zrun: automatically uncompress arguments to command Wth do they do? What does any of this means? I know tee but have no idea what « tee stdin to pipes » would do

oftenwrong 5y ago
You will want to read the man pages. 'pee' is straightforward to understand if you already understand 'tee'. 'pee' is used to pipe output from one command to two downstream commands. https://en.wikipedia.org/wiki/Tee_(command) https://en.wikipedia.org/wiki/Tee_(command)
- thiht 5y ago
  I know tee but have no idea what pee would do considering this description. From your description I guess something like « pee a b » would be the same as « a | b »? If so that’s cool, but the one line descriptions definitely need a rework.
  - nerdponx 5y ago
    I believe it's more like `a | pee b x y z | c`. This would run `b x y x` as well as `c` using the output from `a`. I think Zsh supports this natively with its "multios" option, `a > >(b c y z) > >(c)`. But then you have to write the rest of your pipe inside the ().
  - somat 5y ago
    I can only guess from that description is that it is the cat command.
  - oftenwrong 5y ago
    It loosely follows the same metaphor as the T-shaped pipe connector that 'tee' is named for. $ seq 3 | tee somefile 1 2 3 ╔═somefile seq═tee═╣ ╚═stdout $ seq 10 | pee 'head -n 3' 'tail -n 3' 1 2 3 8 9 10 ╔═head═╗ seq═pee═╣ ╠═stdout ╚═tail═╝
- somat 5y ago
  The unix shell was designed to optimize for simple pipes. to make pipe networks you usually have to use named pipes, aka fifos. I once had to use an IBM mainframe shell(cms If I remember correctly) which had pipes however IBM in their infinite wisdom decided to make the pipe network the primary interface, while this made complex pipes a bit less awkward, simple(single output) pipes were wordy compared to the unix equivalent.
chriswarbo 5y ago
`ts` is like `cat`, but each line gets prefixed with a timestamp of when that line was written. Useful when writing to log files, or finding which step of a program is taking the most time. `sponge` allows a command to overwrite a file in-place; e.g. if we want to replace the contents of myfile.txt, to only keep lines containing 'hello', we might try this: grep 'hello' < myfile.txt > myfile.txt However, this won't work: as soon as grep finds the first matching line, the entire contents of the file will be overwritten, preventing any more from being found. The `sponge` command waits until its stdin gets closed, before writing any output: grep 'hello' < myfile.txt | sponge > myfile.txt

by thiht 5y ago

oftenwrong 5y ago

You will want to read the man pages. 'pee' is straightforward to understand if you already understand 'tee'. 'pee' is used to pipe output from one command to two downstream commands. https://en.wikipedia.org/wiki/Tee_(command) https://en.wikipedia.org/wiki/Tee_(command)

thiht 5y ago
I know tee but have no idea what pee would do considering this description. From your description I guess something like « pee a b » would be the same as « a | b »? If so that’s cool, but the one line descriptions definitely need a rework.
- nerdponx 5y ago
  I believe it's more like `a | pee b x y z | c`. This would run `b x y x` as well as `c` using the output from `a`. I think Zsh supports this natively with its "multios" option, `a > >(b c y z) > >(c)`. But then you have to write the rest of your pipe inside the ().
- somat 5y ago
  I can only guess from that description is that it is the cat command.
- oftenwrong 5y ago
  It loosely follows the same metaphor as the T-shaped pipe connector that 'tee' is named for. $ seq 3 | tee somefile 1 2 3 ╔═somefile seq═tee═╣ ╚═stdout $ seq 10 | pee 'head -n 3' 'tail -n 3' 1 2 3 8 9 10 ╔═head═╗ seq═pee═╣ ╠═stdout ╚═tail═╝
somat 5y ago
The unix shell was designed to optimize for simple pipes. to make pipe networks you usually have to use named pipes, aka fifos. I once had to use an IBM mainframe shell(cms If I remember correctly) which had pipes however IBM in their infinite wisdom decided to make the pipe network the primary interface, while this made complex pipes a bit less awkward, simple(single output) pipes were wordy compared to the unix equivalent.

chriswarbo 5y ago

`ts` is like `cat`, but each line gets prefixed with a timestamp of when that line was written. Useful when writing to log files, or finding which step of a program is taking the most time. `sponge` allows a command to overwrite a file in-place; e.g. if we want to replace the contents of myfile.txt, to only keep lines containing 'hello', we might try this: grep 'hello' < myfile.txt > myfile.txt However, this won't work: as soon as grep finds the first matching line, the entire contents of the file will be overwritten, preventing any more from being found. The `sponge` command waits until its stdin gets closed, before writing any output: grep 'hello' < myfile.txt | sponge > myfile.txt