>export FOOBAR=foobar; IFS=b echo ${FOOBAR}
I was expecting to see
foo ar
but I see
foobar
Why?
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2 Answers
The IFS hasnt yet taken effect. add another ";":
FOOBAR=foobar IFS=b; echo ${FOOBAR}
In man bash section SIMPLE COMMAND EXPANSION
you can read (abbreviated):
When a simple command is executed
The words that the parser has marked as variable assignments (those preceding the command name) are saved for later processing.
The words that are not variable assignments or redirections are expanded.
...
The text after the = in each variable assignment ... [are] assigned to the variable.
so the IFS=b is done after expanding $FOOBAR.
2 Comments
Charles Duffy
Excellent. As-amended, no need for me to maintain my own answer here.
Adrian
This can't be the answer. From a little further along in that same part of the man page: "Otherwise, the variables are added to the environment of the executed command and do not affect the current shell environment." Which means that the command being executed should see the
IFS variable as was assigned, and wouldn't be seen after the command has been invoked. Otherwise, what would be the point of having this feature?[edit]I removed the technically incorrect answer.
http://tldp.org/LDP/abs/html/internalvariables.html "This variable determines how Bash recognizes fields, or word boundaries, when it interprets character strings."
4 Comments
Charles Duffy
All unquoted expansions are string-split (unless in
[[ ]] or other special syntax suppressing that behavior); no loops needed.
Lizardx
I didn't say a loop was needed, I said, ie, which means, for example, a loop. However, with that said, I see the error in my reply.
Charles Duffy
Certainly, but you imply very strongly that
echo $FOOBAR does not, in and of itself, string-split the value in FOOBAR before passing those values to echo. This implication is incorrect.Charles Duffy
...by contrast, @meuh's answer -- preceding yours by two minutes -- is spot-on for accuracy; the only reason I added my own was that it's potentially lacking on completeness.