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SH: two variables in for loop

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# 1  
Old 07-30-2008
SH: two variables in for loop
Hi, say I have a simple sh script like this:

Code:
for i in a b c d
        do
                for j in 1 2 3 4
                        do
                                echo "$i $j"
                        done
        done

and the output is

Code:
 a 1
 a 2
 a 3
 a 4
 b 1
 b 2
 b 3
 b 4
 c 1
 c 2
 c 3
 c 4
 d 1
 d 2
 d 3
 d 4

how do i make its output like this?

Code:
a 1
b 2
c 3
d 4

TIA
# 2  
Old 07-30-2008

Don't use two loops.

Code:
n=1
for l in a b c d
do
   printf "%s %d\n" "$l" "$n"
   n=$(( $n + 1 ))
done

# 3  
Old 07-30-2008
Thanks, I need to re-qualify my question:

what if its not a number and you can't do math on it?

e.g.
list1:
Code:
mary
eve
delilah

list2:
Code:
joseph
adam
samson

output:
Code:
mary joseph
adam eve
samson delilah


Code:
for i in `cat list1`; ... for j in `cat list2`; ... do ... print $i $j ... done

any way around this?
Last edited by rbatte1; 09-21-2016 at 07:47 AM.. Reason: Added CODE tags
# 4  
Old 07-31-2008
Quote:
Originally Posted by marcpascual
Thanks, I need to re-qualify my question:

what if its not a number and you can't do math on it?

e.g.
list1:
Code:
mary
eve
delilah

list2:
Code:
joseph
adam
samson

output:
Code:
mary joseph
adam eve
samson delilah


Code:
for i in `cat list1`; ... for j in `cat list2`; ... do ... print $i $j ... done

any way around this?
Code:
set -f
IFS='
'
set -- $( cat list2 )
for i in `cat list1`
do
  printf "%s %s\n" "$i" "$1"
  shift
done

Last edited by rbatte1; 09-21-2016 at 07:47 AM..
This User Gave Thanks to cfajohnson For This Post:
Vinay Kumar K S
# 5  
Old 07-31-2008
amazing, thank you!
# 6  
Old 07-31-2008
Quote:
Originally Posted by cfajohnson
Code:
set -f
IFS='
'
set -- $( cat list2 )
for i in `cat list1`
do
  printf "%s %s\n" "$i" "$1"
  shift
done

KISS principle states that design simplicity should be a key goal and unnecessary complexity avoided. Smilie
Code:
paste -d ' ' list1 list2

Last edited by danmero; 07-31-2008 at 12:40 AM..
# 7  
Old 08-01-2008
Quote:
Originally Posted by marcpascual
how do i make its output like this?

Code:
a 1
b 2
c 3
d 4

It seems you can't have multiple "x in y" terms in a for loop, so the next best thing is probably to rewrite the loop as an index iterator:
Code:
is=(a b c d)
js=(1 2 3 4)

for ((i = 0; i < 4; i++)) 
	do echo ${is[i]} ${js[i]}
done

It's not as nice, but still relatively easy to read, especially if you define your lists together. Smilie
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