Unset IFS value for shell script

Question

In my use case I would like to change the value of IFS to a known separator (-). I tried the following:

OLDIFS=$IFS
IFS='-'
for x in $*
do
    echo $x
done
IFS=$OLDIFS

When using e.g. -a b -c d as input string I expect the output to be

a b
c d

However, what I get is

a
b
c
d

I'm on AIX.

Make sure you pass one argument to your shell script. `./foo "-a b -c d"` should produce the result you want — Brandin, Apr 29 '14 at 10:52
Your expected result is wrong, this would return an empty line, followed by `a b ` followed by `c d`. If you remove the whitespaces from `IFS` they will not be used as separators resulting in an empty first token and a trailing space in the second token. — Adrian Frühwirth, Apr 29 '14 at 11:14
Yes No problem for the empty line i just want to return an atomic token `a b` @AdrianFrühwirth — Aymanadou, Apr 29 '14 at 11:17
@AdrianFrühwirth actually in my usecase `a` is a parameter and `b` is the value of this parameter, so as a first step i want to tokenize my argument list to get parm|value in one token(no problem with trailing white spaces ...) in a second step i will split this token in parms and value — Aymanadou, Apr 29 '14 at 13:24
@DevSolar i have the same version 6.1 and i always reproduce — Aymanadou, Apr 29 '14 at 13:30
@Aymanadou Oh...please don't bake your own arguments parser, use [`getopts`](http://stackoverflow.com/a/16496491/612462) instead. — Adrian Frühwirth, Apr 29 '14 at 13:35

score 1 · Answer 1 · answered Apr 29 '14 at 10:52

1

I tried your code and I get

a b
c d

Try this

$ cat >a <<.
#!/bin/sh
OLDIFS=$IFS
IFS='-'
for x in $*
do
    echo $x
done
IFS=$OLDIFS
.
$ chmod +x a
$ ./a "-a b -c d"

a b
c d
$

answered Apr 29 '14 at 10:52

PeterMmm

I am in AIX envirement and i get the bad result. – Aymanadou Apr 29 '14 at 11:01
And what shell you are using ? – PeterMmm Apr 29 '14 at 11:05
What shell are you using for launching your shell script, and what shell are you using for running your shell script (what is after the shebang) (these can be different) – Brandin Apr 29 '14 at 11:05
i tried #!/bin/ksh and #!/bin/sh both of themm gave the same bad result – Aymanadou Apr 29 '14 at 11:08

score 1 · Answer 2 · answered Apr 29 '14 at 13:06

1

Here is one way of getting this output using awk and avoid all the IFS manipulation:

s='-a b -c d'
echo "$s" | awk -F ' *- *' '{print $2 RS $3}'
a b
c d

answered Apr 29 '14 at 13:06

anubhava

2 Answers2