Evaluating or expanding a variable to get its value. Depending on the language, a variable may be expanded one or more times.
Questions tagged [variable-expansion]
246 questions
3
votes
2 answers
How to keep strings quoted in bash parameters
I have a Bash script which passes patterns and switches to grep.
#!/bin/bash
foo() {
grep $@ *.txt
}
foo $@
And, of course, myscript SomeText works but myscript "Text1 Text2" does not. Is there a way to keep the quotes when passing arguments…
jackhab
- 17,128
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3
votes
2 answers
Shell parameter expansion: how can I get the file name without the directory part?
I was writing a makefile and suppose I have the following;
FILES = file1.py \
folder1/file2.py \
folder2/file3.py
And I have the following for loop:
-@for file in $(FILES); do \
echo $${file/folder1\/}; \
done
The above…
user945216
- 251
- 3
- 14
2
votes
0 answers
How to make properly designed survey objects?
I´m trying to use the srvyr package in R. The data is extracted from this link:
Expenses: https://cdn.bancentral.gov.do/documents/estadisticas/encuesta-de-gastos-e-ingresos/documents/Cuadros_Gastos.xlsx?v=1689283267553
Income: …
almr27
- 43
- 4
2
votes
2 answers
bash - array expansion and function calls
SETUP:
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin21)
Copyright (C) 2007 Free Software Foundation, Inc.
TEST:
check_this() { echo " FIRST: {$1} SECOND: {$2} THIRD: {$3}"; }
foo=(1 2 3)
expression="${foo[@]}"
echo "via…
Frank-Rene Schäfer
- 3,182
- 27
- 51
2
votes
1 answer
How to use a string with arguments to call a script as bash would do it when interprets the command line?
The desired outcome
Is there a way to use a string that contains the arguments to call a script?
str_params="this/one 'that one' and \"yet another\""
The function below prints feedback on the stdout on how the arguments were received:
display_args…
rellampec
- 698
- 6
- 22
2
votes
2 answers
Expansion of C preprocessor macros with integer arithmetic in a text file?
On my system, I have a /usr/include directory, with a curl/options.h file in it, which contains a preprocessor definition of CURLOT_FLAG_ALIAS.
If I have the following test.txt:
#include "curl/options.h"
curlot flag alias is:…
sdbbs
- 4,270
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2
votes
5 answers
How to write bash function to print and run command when the command has arguments with spaces or things to be expanded
In Bash scripts, I frequently find this pattern useful, where I first print the command I'm about to execute, then I execute the command:
echo 'Running this cmd: ls -1 "$HOME/temp/some folder with spaces'
ls -1 "$HOME/temp/some folder with…
Gabriel Staples
- 36,492
- 15
- 194
- 265
2
votes
1 answer
Nested parameter expansion not working as expected
zsh says:
${name}
The value, if any, of the parameter name is substituted.
It then also says:
If a ${...} type parameter expression or a $(...) type command substitution is used in place of name above, it is expanded first and the result is used…
abjoshi - Reinstate Monica
- 372
- 1
- 13
2
votes
1 answer
Using variables as command arguments in zsh
I'm trying to write a function for zsh to find files with fzf and directly open them in my editor.
The arguments for the call to fzf are stored in a variable like so:
FZF_FILE_PREVIEW="--preview 'cat {}) 2> /dev/null | head -200'"
the function…
namron
- 75
- 7
2
votes
1 answer
Parameter expansion for find command
Consider the code (the variable $i is there because it was in a loop, adding several conditions to the pattern, e.g. *.a and *.b, ... but to illustrate this problem only one wildcard pattern is enough):
#!/bin/bash
i="a"
PATTERN="-name bar -or…
wmnorth
- 247
- 4
- 9
2
votes
2 answers
How can I check if exists file with name according to "template" in the directory?
Given variable with name template , for example: template=*.txt.
How can I check if files with name like this template exist in the current directory?
For example, according to the value of the template above, I want to know if there is files…
AskMath
- 415
- 1
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- 11
2
votes
2 answers
PowerShell using a variable in quotes within a command
I have this which works (triple double quotes are not a mistake; it works exactly like this)—concentrate on the Start-Process part:
Start-Process powershell -Credential $cred -WorkingDirectory "$lettre_disque" -ArgumentList '-noprofile -command…
Rakha
- 1,874
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- 60
2
votes
2 answers
zsh Looping through multiple parameters
In my old .bashrc, I had a short section as follows:
PATH2ADD_SCRIPTBIN="/home/foo/bar/scriptbin"
PATH2ADD_PYTHONSTUFF="/home/foo/bar/pythonprojects"
PATH2ADDLIST="$PATH2ADD_SCRIPTBIN $PATH2ADD_PYTHONSTUFF"
for PATH2ADD in $PATH2ADDLIST; do
…
Trevor Sears
- 459
- 8
- 24
2
votes
1 answer
How to escape special characters in a variable to provide commandline arguments in bash
I very often use find to search for files and symbols in a huge source tree. If I don't limit the directories and file types, it takes several minutes to search for a symbol in a file. (I already mounted the source tree on an SSD and that halved the…
NZD
- 1,780
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2
votes
2 answers
Bash - How to force literal in subshell string?
I'd like to control variable expansion when executing a shell command using sudo bash -c.
I know I can do it from a normal shell:
bash$ export FOO=foo
bash$ export BAR=bar
bash$ echo "expand $FOO but not "'$BAR'""
expand foo but not $BAR
How can I…
shj
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