74

It's probably a lame question. But I am getting 3 arguments from command line [ bash script ]. Then I am trying to use these in a for loop.

for i in {$1..$2}
    do action1
done

This doesn't seem to work though and if $1 is "0" and $2 is 2 it prints {0..2}' and calls action1` only once. I referred to various examples and this appears to be the correct usage. Can someone please tell me what needs to be fixed here?

starball
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ru4mqart668op514
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7 Answers7

85

You can slice the input using ${@:3} or ${@:3:8} and then loop over it

For eg., to print arguments starting from 3

for i in ${@:3} ; do echo $i; done

or to print 8 arguments starting from 3 (so, arguments 3 through 10)

for i in ${@:3:8} ; do echo $i; done
Bort
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Vijayender
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82

How about:

for i in $(eval echo {$1..$2}); do echo $i; done
zxt
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    I would recommend against using eval and consider splicing up the arguments as suggested in Vijayender's answer. – Yogarine Jan 26 '22 at 11:12
24

Use the $@ variable?

for i in $@
do
    echo $i
done

If you just want to use 1st and 2nd argument , just

for i in $1 $2

If your $1 and $2 are integers and you want to create a range, use the C for loop syntax (bash)

for ((i=$1;i<=$2;i++))
do
...
done
kurumi
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    You might want to only include the second part of the answer - It's better than using `eval` and fits the question. – l0b0 Oct 14 '11 at 07:38
15

I had a similar problem. I think the issue is with dereferencing $1 within the braces '{}'. The following alternative worked for me ..

#!/bin/bash
for ((i=$1;i<=$2;i++))
do
   ...
done

Hope that helps.

rthere
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  • +1 IMO This is cleaner than having to `eval` as in the accepted answer, but the accepted answer is more specific to the OP – nhed Oct 02 '13 at 16:48
2
for i in `seq $1 $2`; do echo $i; done
John Karasev
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0
#/bin/bash
for i
do
  echo Value: $i
done

This will loop over all arguments given to the script file. Note, no "do" or anything else after the loop variable i.

Rolf Ø
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0

I recommend this: In loop we handle only $1, and do shift N times (if arguments will be need next, then better save it, because shift removing argument):

for a in 1 2 3
do
echo $1
shift
done

Example: ./test.sh "abra k" "b 2" "c 14"

abra k
b 2
c 14
Avatar Mod
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