All Questions
87 questions
0
votes
1
answer
42
views
What is (if any) the file descriptor of /dev/tty?
The urgent issue to read keyboard input in the pipeline is solved by the answer in https://stackoverflow.com/questions/15230289/read-keyboard-input-within-a-pipelined-read-loop:
mycommand-outputpiped |...
- 1,363
3
votes
1
answer
153
views
How to ensure that SSH client leave stdout file descriptor clean for reuse?
This code terminates with error :
(
ssh localhost seq 100000
seq 100000
) | wc
#-> seq: write error: Resource temporarily unavailable
This is a minimal code to reproduce the write error.
...
- 832
5
votes
2
answers
504
views
What is the difference between `{ echo err >&2; echo out >&1; } | :` and `{ echo out >&1; echo err >&2; } | :` in Bash?
Why can the command { echo err >&2; echo out >&1; } | : print "err", but the second can not?
Some tests in container:
Debian: 11.5 (bash/5.1.4)
Rocky Linux: 9.0 (bash/5.1.8),
...
- 53
-1
votes
1
answer
36
views
Create multi-command pipeline producer command
Kind of blanking on how to do this right:
{
echo Hello1;
usleep 500000 ;# sleep 500,000 microseconds
echo Hello2;
} | node break-out-of-loop.js
I just want to issue some stdin and delay ...
- 10.6k
-3
votes
1
answer
255
views
Extract an ID that matches the user login from a table on shell script
So, I have all these user login information (service, admin, J009878) and this table you see here comes from another command whose output is this table which I save in file.txt. What I want to achieve ...
- 23
1
vote
2
answers
484
views
Print output of httpie command, then pipe to grep
how can I print output of httpie request then pipe to grep to check if request has succeeded or failed?
http --print=hb POST http://localhost:8080 | grep -c "HTTP/1.1 200" && echo &...
- 113
2
votes
0
answers
446
views
bash: writing to the file descriptor #3 of an unnamed (anonymous) pipe
I need to call a PHP interpreter, which is in a docker container, from my Linux host system. For some reasons I don't want to install PHP on the host system. Now I'm trying to call PHP in this way:
...
- 21
1
vote
2
answers
454
views
In Bash, how can I compute and capture the result from an intermediate node in a pipeline?
In Bash, how can I compute and capture the result from an intermediate node in a pipeline?
For example, given a list of integers and a command or function maximum, using a single Bash pipeline, how ...
- 567
4
votes
1
answer
688
views
PIPESTATUS variable is empty
I'm working on a Linux server and noticed that the PIPESTATUS array variable is always empty.
I'm on bash v4.1.2(1)-release
$ echo $BASH_VERSION
4.1.2(1)-release
$ false | true | false
$ echo ${...
- 163
3
votes
1
answer
9k
views
Shell pipe with "echo" [duplicate]
Can someone explain me, why the following doesn't work:
echo hello | echo -
Just for learning purposes (don't tell me to use something else and not "echo" or why do I need it), I want to ...
- 161
1
vote
1
answer
1k
views
/bin/sh closes immediately without waiting for user input
I am exploiting a Buffer Overflow vulnerability for educational purposes. My goal is to trigger a shell by changing the RIP and targeting the evil function. I am using Ubuntu 18.04 64-bits. Here is ...
- 220
0
votes
2
answers
3k
views
How can I read from named pipe line by line and exit?
I have the following bash script that I'd like to use as a fuzzy file opener. I create a fifo, spawn a new terminal with fzf running and redirect fzf's output to the fifo. I then call a function that ...
- 407
1
vote
1
answer
982
views
Use piped content in a python script passed as heredoc
I am aware that here-doc goes to stdin. I saw that here-doc takes precedence in going to stdin before what's coming from the pipe (see below).
But maybe there's a trick to make it work?
All in all I ...
- 21
2
votes
1
answer
242
views
Redirecting to `stdin`: who outputs the contents afterwards?
Consider the following example in Bash shell
$ echo 'test' | wc -c
5
Everything works as expected. Now let's change it to
$ echo 'test' >&0 | wc -c
test
0
Now, that 0 in the output makes ...
2
votes
3
answers
2k
views
How to pass two stdin to sudo?
My goal is to write something to a file that needs superuser privileges and I want to do it with a single line of code. Steps I have tried:
I can pass a password from stdin to sudo by using its -S ...
- 119