CODEWITHSUNDEEP
bashbrace-expansion
zjhui
zjhui

Reputation: 809

bash's brace-expansion didn't work

i have a simple problem with bash's brace expansion: 

#!/bin/bash  
PICS="{x1,x2,x3}.jpg {y1,y2}.png"    
for i in $PICS  
do  
  echo $i  
done

but the result is:
{x1,x2,x3}.jpg
{y1,y2}.png
But i want the result is: x1.jpg x2.jpg x3.jpg y1.png y2.png
what should i do ?

Upvotes: 1

Views: 181

Answers (4)

ormaaj
ormaaj

Reputation: 6577

These are files which already exist? If yes, you probably want a (ext)glob. E.g. 

printf '%s\n' [xy]+([[:digit:]]).@(jp|pn)g

Brace expansion in Bash is the first expansion step. It occurs mostly in unquoted contexts, though the exact rules are complex. You cannot store one in a string unless you eval the result later.

printf '%s\n' {x{1..3}.jp,y{1,2}.pn}g

These can be defined however you feel. See other answers for less obfuscated options.

You also need to quote your expansions.

Upvotes: 0

digitalvision
digitalvision

Reputation: 2622

Brace and wildcard expansion is performed for arguments when a command is evaluated. Change the first line to:

PICS=$(echo {x1,x2,x3}.jpg {y1,y2}.png)

Upvotes: 1

Gilles Quénot
Gilles Quénot

Reputation: 185106

The straightforward way is 

#!/bin/bash  

for i in {x1,x2,x3}.jpg {y1,y2}.png; do
  echo $i  
done

Upvotes: 5

Simon Richter
Simon Richter

Reputation: 29578

Brace expansion is performed while parsing the line, and will not happen inside quotes.

Upvotes: 3

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