All Questions
105 questions
3
votes
2
answers
86
views
print_one_line_and_wait_long_time | head -n1: early exit of pipe/process substitution [duplicate]
tl;dr: How to reliably ensure that the pipe a | head -n1 terminates as soon as head terminates?
Motivation: git log --grep="$MAIL_SUBJECT_LINE" --oneline --format=%H | head -n1 takes a long ...
- 361
0
votes
2
answers
86
views
Piping output to bash script
I'm going through the "sed & awk" book by Dougherty and Robbins. One of the examples calls for piping output to a shell script:
sed -f nameState list | byState
But I've found that, in ...
- 103
2
votes
1
answer
76
views
Is there a way to `exec` a pipeline or exit shell after launching a pipeline?
I'm writing a shell wrapper script that is supposed to act as a pager (receiving input on stdin and performing output on a tty).
This wrapper prepares environment and command lines, then launches two ...
- 5,659
0
votes
1
answer
60
views
find with execdir, pipe redirection evaluated too early (quote issue?)
I use multiple GitHub accounts at work, so I need to modify the remote url to add my work account. I have figured out the recursive find -execdir, and how to get/sed/set the remote url, but I cannot ...
- 231
0
votes
0
answers
790
views
Understanding bash read variable substitution [duplicate]
First of all, I have little experience using Bash and I apologize for my bad English.
Maybe it's obvious.
I am trying to understand why Bash drop value of the variable in this oneliner.
echo "...
- 1
0
votes
0
answers
27
views
Bash equivalent of zsh alias at end of command (for pipes) [duplicate]
In zsh, I can set an alias at the end of a command, e.g. making G pipe through grep or L pipe through less.
Can I do something similar in bash? E.g. ls G key would expand to ls | grep key or ls L ...
- 133
0
votes
2
answers
1k
views
Get exit status of the first command in a pipeline *in the second command*
My question is similar to Get exit status of process that's piped to another, but I want to get the exit status of the first command in the pipe within the pipe.
Here's an example:
false | echo &...
- 103
1
vote
4
answers
156
views
How can I use else for `ifne`?
ifne - Run command if the standard input is not empty
If possible I want to run command if the standard input is empty as well; else section for ifne.
$ printf "hello" | ifne echo "...
- 507
0
votes
0
answers
78
views
Creating a script which compares the return value from an AT command
I am trying to write a shell script that can save the output of a piped process to a variable. This variable is then compared to a known string in order to discern whether or not my AT modem is ...
1
vote
1
answer
961
views
Teeing each output while capturing return exit code (are any env variable) and passing it back "up the chain"
I've been struggling and reading quite a bit about this, and clearly bash is probably not the best tool for this, but since I'm already dug this deep into this hole (too much of the code is already ...
- 748
1
vote
4
answers
310
views
How to use a value from sub shell in parent shell
I'm not used to linux scripting and this is the first time I'm working on it so I'm struggling with the following problem:
Code:
while [ $pct -gt 80 ]; do
flag=1;
ls -tr | while read file; do
...
0
votes
2
answers
466
views
Unable to match a specific regex with bash
I have a txt file with content as such:
Adedunmola Okikiola Adewole 512.035
215−39 ^M
Ademir Cleto de Oliveira 055.735
445−13 ^M
Adilson ...
- 143
0
votes
2
answers
326
views
Incremental reading from pipe
Trying to figure out how to have a shell script only take fix-length blocks out of stdin. I would have thought something like this would have worked, but it does not:
#!/bin/bash
value=0
while [ &...
- 653
1
vote
0
answers
112
views
How to extract a value from a piped output to a variable repeatedly while the output is still being written
I want to update the download status at every 5 second of file to my telegram bot. Also here I'm using bash.
aria2c $url --summary-interval=5 2>&1 | tee output.log | grep -oP "(\d+(\.\d+)?(...
- 21
2
votes
1
answer
558
views
File descriptor 10 when running a script (Bash/dash, etc.)
When the script runs, a file descriptor 10 appears with the contents of the executable script.
For example, the script:
#!/bin/sh
sleep 600
When viewing the fd of a running script through processes, ...
- 157