Trying to understand how to work with IFS

up vote
2
down vote

favorite

I'm trying to understand how to work with the shell variable IFS. I have the following code:

#!/bin/bash

ourpath=$PATH
oldIFS=$IFS
IFS=":"
echo "ourpath = $ourpath"
for directory in "$ourpath"; do
 echo "directory = $directory"
done

IFS=$oldIFS

Running this using bash test.sh yields:

ourpath = ~/bin:/home/<user>/anaconda3/bin:/home/<user>/.local/bin:/home/<user>/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:~/scripts
directory = ~/bin:/home/<user>/anaconda3/bin:/home/<user>/.local/bin:/home/<user>/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:~/scripts

But I would expect directory to loop over the directories in $PATH because it should be split by :. What is going wrong here?

asked 27 mins ago

Hunter

1134

New contributor

add a commentÂ |Â

up vote
2
down vote

favorite

I'm trying to understand how to work with the shell variable IFS. I have the following code:

#!/bin/bash

ourpath=$PATH
oldIFS=$IFS
IFS=":"
echo "ourpath = $ourpath"
for directory in "$ourpath"; do
 echo "directory = $directory"
done

IFS=$oldIFS

Running this using bash test.sh yields:

ourpath = ~/bin:/home/<user>/anaconda3/bin:/home/<user>/.local/bin:/home/<user>/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:~/scripts
directory = ~/bin:/home/<user>/anaconda3/bin:/home/<user>/.local/bin:/home/<user>/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:~/scripts

But I would expect directory to loop over the directories in $PATH because it should be split by :. What is going wrong here?

asked 27 mins ago

Hunter

1134

New contributor

add a commentÂ |Â

up vote
2
down vote

favorite

I'm trying to understand how to work with the shell variable IFS. I have the following code:

#!/bin/bash

ourpath=$PATH
oldIFS=$IFS
IFS=":"
echo "ourpath = $ourpath"
for directory in "$ourpath"; do
 echo "directory = $directory"
done

IFS=$oldIFS

Running this using bash test.sh yields:

ourpath = ~/bin:/home/<user>/anaconda3/bin:/home/<user>/.local/bin:/home/<user>/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:~/scripts
directory = ~/bin:/home/<user>/anaconda3/bin:/home/<user>/.local/bin:/home/<user>/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:~/scripts

But I would expect directory to loop over the directories in $PATH because it should be split by :. What is going wrong here?

asked 27 mins ago

Hunter

1134

New contributor

I'm trying to understand how to work with the shell variable IFS. I have the following code:

#!/bin/bash

ourpath=$PATH
oldIFS=$IFS
IFS=":"
echo "ourpath = $ourpath"
for directory in "$ourpath"; do
 echo "directory = $directory"
done

IFS=$oldIFS

Running this using bash test.sh yields:

ourpath = ~/bin:/home/<user>/anaconda3/bin:/home/<user>/.local/bin:/home/<user>/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:~/scripts
directory = ~/bin:/home/<user>/anaconda3/bin:/home/<user>/.local/bin:/home/<user>/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:~/scripts

But I would expect directory to loop over the directories in $PATH because it should be split by :. What is going wrong here?

bash shell-script scripting

asked 27 mins ago

Hunter

1134

New contributor

asked 27 mins ago

Hunter

1134

New contributor

asked 27 mins ago

Hunter

1134

New contributor

asked 27 mins ago

Hunter

1134

asked 27 mins ago

Hunter

1134

New contributor

Hunter is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a commentÂ |Â

1 Answer
1

active

oldest

votes

up vote
3
down vote

accepted

It's the exact same as with space: You have quoted $directory and it doesn't get split. If you remove the quotes then it will give you the result you're looking for.

I.e:

for directory in $ourpath ; do
 echo "directory = $directory"
done

Bonus points: It won't matter if $ourpath contains spaces because IFS is :, so it will only be split over :

answered 25 mins ago

V13

2,275612

Thank you! It works now. I got this (simplified) example from "Wicked Cool Shell Scripts: 101 Scripts for Linux, OS X, and UNIX Systems" by Dave Taylor and Brandon Perry (page 11), where they also quote ourpath. I wonder if that is a mistake on their behave or if I'm doing something else wrong.
â€“Â Hunter
11 mins ago

add a commentÂ |Â

Your Answer

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "106"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
convertImagesToLinks: false,
noModals: false,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);

);

Hunter is a new contributor. Be nice, and check out our Code of Conduct.

draft saved

draft discarded

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f475341%2ftrying-to-understand-how-to-work-with-ifs%23new-answer', 'question_page');

);

Post as a guest

Name

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

up vote
3
down vote

accepted

It's the exact same as with space: You have quoted $directory and it doesn't get split. If you remove the quotes then it will give you the result you're looking for.

I.e:

for directory in $ourpath ; do
 echo "directory = $directory"
done

Bonus points: It won't matter if $ourpath contains spaces because IFS is :, so it will only be split over :

answered 25 mins ago

V13

2,275612

Thank you! It works now. I got this (simplified) example from "Wicked Cool Shell Scripts: 101 Scripts for Linux, OS X, and UNIX Systems" by Dave Taylor and Brandon Perry (page 11), where they also quote ourpath. I wonder if that is a mistake on their behave or if I'm doing something else wrong.
â€“Â Hunter
11 mins ago

add a commentÂ |Â

up vote
3
down vote

accepted

It's the exact same as with space: You have quoted $directory and it doesn't get split. If you remove the quotes then it will give you the result you're looking for.

I.e:

for directory in $ourpath ; do
 echo "directory = $directory"
done

Bonus points: It won't matter if $ourpath contains spaces because IFS is :, so it will only be split over :

answered 25 mins ago

V13

2,275612

Thank you! It works now. I got this (simplified) example from "Wicked Cool Shell Scripts: 101 Scripts for Linux, OS X, and UNIX Systems" by Dave Taylor and Brandon Perry (page 11), where they also quote ourpath. I wonder if that is a mistake on their behave or if I'm doing something else wrong.
â€“Â Hunter
11 mins ago

add a commentÂ |Â

up vote
3
down vote

accepted

It's the exact same as with space: You have quoted $directory and it doesn't get split. If you remove the quotes then it will give you the result you're looking for.

I.e:

for directory in $ourpath ; do
 echo "directory = $directory"
done

Bonus points: It won't matter if $ourpath contains spaces because IFS is :, so it will only be split over :

answered 25 mins ago

V13

2,275612

It's the exact same as with space: You have quoted $directory and it doesn't get split. If you remove the quotes then it will give you the result you're looking for.

I.e:

for directory in $ourpath ; do
 echo "directory = $directory"
done

Bonus points: It won't matter if $ourpath contains spaces because IFS is :, so it will only be split over :

answered 25 mins ago

V13

2,275612

answered 25 mins ago

V13

2,275612

answered 25 mins ago

V13

2,275612

answered 25 mins ago

V13

2,275612

Thank you! It works now. I got this (simplified) example from "Wicked Cool Shell Scripts: 101 Scripts for Linux, OS X, and UNIX Systems" by Dave Taylor and Brandon Perry (page 11), where they also quote ourpath. I wonder if that is a mistake on their behave or if I'm doing something else wrong.
â€“Â Hunter
11 mins ago

add a commentÂ |Â

Thank you! It works now. I got this (simplified) example from "Wicked Cool Shell Scripts: 101 Scripts for Linux, OS X, and UNIX Systems" by Dave Taylor and Brandon Perry (page 11), where they also quote ourpath. I wonder if that is a mistake on their behave or if I'm doing something else wrong.
â€“Â Hunter
11 mins ago

Thank you! It works now. I got this (simplified) example from "Wicked Cool Shell Scripts: 101 Scripts for Linux, OS X, and UNIX Systems" by Dave Taylor and Brandon Perry (page 11), where they also quote ourpath. I wonder if that is a mistake on their behave or if I'm doing something else wrong.
â€“Â Hunter
11 mins ago

add a commentÂ |Â

Hunter is a new contributor. Be nice, and check out our Code of Conduct.

draft saved

draft discarded

Hunter is a new contributor. Be nice, and check out our Code of Conduct.

draft saved

draft discarded

Post as a guest

Name

Search This Blog

Iyfjky