Command substitution is the replacement of a command with the result returned after it is evaluated.
Questions tagged [command-substitution]
234 questions
0
votes
1 answer
Shell script when we need to quote or unquote
I am trying to understand in what situation we should use quote the command while parsing the output from it or when should not.
bash
Case 1:
I am using below command into my bash script which works well while using like below which results the…
user2023
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0
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3 answers
BASHRC PS1 show datetime but plus 3 hours
Every of us set own convenience working with Linux shell, for example I use
/root/.bashrc
PS1='[\h:\w] \D{%F %T}\n\$ '
to show servername + current server datetime + newline for command - so it looks like
[servername217:~] 2022-02-06…
Serge
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0
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2 answers
How effectlively to call a bash function to another in a program
I have below Bash script where I am trying to Create functions for creating colors for output text in the script, I am trying to call these function into another one but somehow its not working.
I looked around and googled, but didn't get the…
user2023
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0
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2 answers
bash zip file with version read from file and used in zip file name
I'm able to zip a bunch of files with zip
$ zip build.zip src/*.js src/assets/icons/*.png *.json
updating: src/addReactionsNav.js (deflated 65%)
updating: manifest.json (deflated 55%)
updating: src/assets/icons/icon_128.png (stored 0%)
updating:…
Norfeldt
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0
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1 answer
Bash - optionally set env var in command substitution
The following works without issue:
timestamp=$(TZ=America/New_York date)
echo $timestamp
which (if saved in a file called /tmp/foo) results in:
$ /tmp/foo
Thu Dec 23 21:03:41 EST 2021
This code also works:
timezone=$1
timestamp=$(TZ=$timezone…
Joe Casadonte
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1 answer
How to count amount of pull request made by user?
I have bash sript pull.sh with one argument is github nickname of a person. And I want to count amount of all pull request which was made with this nickname. I select pr this way in command line:
curl -s…
Vivern202
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0
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1 answer
Conditional `if` statement with strings in shell script to configure two computers differently (Ubuntu/Gnome vs Debian/XCFE)
I want to check the current distro in .profile because I have two computers. In one I have Ubuntu with Gnome, and in another I have Debian with XFCE. In either case I want to have different configurations, but I can't manage to even get the…
Daniel
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0
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1 answer
Simple question about ls output and Double quotes
I'm learning bash so this is a simple question probably. I'd like to understand what happens in this case, there's no real use for this script. Let DTEST be a directory that contains some random files.
for filename in " `ls DTEST/*` " ; do
…
user14356197
0
votes
1 answer
why function variable not working in command substitution inside a function?
im running this in bashrc file
function simplefunc () {
output=$(ls -1 "$HOME")
linecount=$(${output} | wc -l)
echo "${linecount}"
echo "${output}"
}
getting this error
Desktop: command not…
darklearner
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0
votes
2 answers
File count in a folder not showing accurate
I am writing a shell script to check two things at one time. The first condition is to check for the existence of a specific file and the second condition is to confirm that there is only one file in that directory.
I am using the following…
Devil's Dream
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votes
1 answer
Passing output of bash expression to variable piped through a dialog progressbox results in null value for the variable
I am using dialog Version: 1.3-20190211 wiht GNU bash, version 5.0.3(1)-release and have the following script snippet which scans for networks on wlan0.
#!/bin/bash
# duplicate file descriptor 1 on file descriptor 3
exec 3>&1
# Scan for networks…
Sirach Matthews
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0
votes
1 answer
How to read in current process with here document
I would like to read in the current process:
mark=one
read a b c <<<$(grep "^$mark " <
blueFast
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0 answers
Bash command substitution within a function does not return the return code from the command substitution
I find that within a function, using command substitution to put the command output in a variable, using $? to get the exit code from the command substitution returns 0, not the returned code.
The command substitution returns the return code as…
0
votes
1 answer
Building filename from command outputs results in ambigous redirect error
I want to edit a file and write it to anoter location without .template at the end. To do so, I use two commands in a row which should give me the new file name, but bash doesn't accept it. I heard you should do this with backquotes but I can't get…
glades
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