For Loop List in Shellscript

Question

I am trying to do something like this in shellscript:

STEP=5
LIST=[1-$STEP]

for i in $LIST
    echo $i
done

The output I expect is:

1 2 3 4 5

I probably have seen this usage before ( e.g. [A-Z] ) but I cannot remember the correct syntax. Thank you for your help!

Like this perhaps: stackoverflow.com/questions/169511/…

minopret
– minopret

2012-02-24 05:34:09 +00:00
Commented Feb 24, 2012 at 5:34 — minopret
– minopret, Commented Feb 24, 2012 at 5:34

ABS · Accepted Answer · 2012-02-24 05:07:56Z

1

Try this. Note that you use the echo command which includes an LF. Use echo -n to get output on the same line as shown

    STEP=5
for i in `seq 1 $STEP`; do

echo $i

done

answered Feb 24, 2012 at 5:07

ABS

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1 Comment

Jens Over a year ago

Note that seq is not a POSIX utility and may not be available. echo -n should never be used; use printf instead, which can portably supress the newline.

glenn jackman · Accepted Answer · 2012-02-24 15:02:26Z

0

Assuming this is bash:

$ echo {1..5}
1 2 3 4 5
$ STEP=5
$ echo {1..$STEP}
{1..5}
$ eval echo {1..$STEP}
1 2 3 4 5

answered Feb 24, 2012 at 15:02

glenn jackman

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5 Comments

dannysauer Over a year ago

This is great until you run it in a directory where there's a file named "1" because some bonehead typo'd a redirect. Then the {1..5} expands to "1" and you spend hours trying to diagnose the problem. :) Unless you use noglob because you've done this before and never want to have that problem again.

Jens Over a year ago

@dannysauer Brace expansion is not file name globbing. echo {1..5} outputs 1 2 3 4 5 whether or not a file named 1 is present. Are you confusing this with echo [1-5]?

glenn jackman Over a year ago

@dannysauer, verify for yourself: the bash sequence of expansions is documented: gnu.org/software/bash/manual/bashref.html#Shell-Expansions

dannysauer Over a year ago

I was probably thinking of a time when I was attempting to do a string comparison using a wildcard (think "{1,2,3}*") and the shell expanded the wildcard to the matching filename rather than preserving the wildcard, screwing up the comparison. Or maybe I was thinking of a variable containing an array index with the brackets, or some other random thing.

dannysauer Over a year ago

To save face, I still maintain that it's a good idea to turn on noglob in shell scripts - only explicitly disabling it when glob-based word expansion is desired. ;)

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