bash array question

dazdaz · 11-20-2008, 08:23 AM

Hi all,

I think this is the correct forum to post this question.

I have a file which is 2 or 4 or 6 lines long, which I would to read all of the contents into a bash shell array.

There are 9 pieces of data per line.

I've seen several examples on the internet however for some reason they don't work.

$ cat /var/tmp/inqraid.out
c6t50060E8010028101d119s2 CL1-B 77010255 169 - s/s/ss 0000 5:05-00 DF600F
c7t50060E8010028105d119s2 CL2-B 77010255 169 - s/s/ss 0000 5:05-00 DF600F

Could someone please write an example of how to read the file into a bash array and I can work from this.

Thanks

colucix · 11-20-2008, 08:42 AM

By something like this?

Code:

#!/bin/bash
declare -a array
array=($(cat "testfile"))

for element in $(seq 0 $((${#array[@]} - 1)))
do
  echo -n "${array[$element]}"
  echo -n " SEP "
  ((count ++))
done

echo
echo "Total number of elements:          " ${#array[@]}
echo "Total number of elements (check):  " $count

dazdaz · 11-20-2008, 09:15 AM

1. The only problem is that I don't have the seq command (Solaris 8 and 10).

2. By the following, echo -n " SEP ", do you mean seperator, which is white-space but not necessarily one space.

colucix · 11-20-2008, 09:35 AM

Quote:

Originally Posted by dazdaz

1. The only problem is that I don't have the seq command (Solaris 8 and 10).

In bash you can try the following brace expansion (it works since bash version 3, only):

Code:

for element in $(eval echo {0..$((${#array[@]} - 1))})

if this does not work, you can always use a while loop which will be executed until $element is equal to the length of the array:

Code:

#!/bin/bash
declare -a array
array=($(cat "testfile"))

element=0
while [ $element -le $((${#array[@]} - 1)) ]
do
  echo -n "${array[$element]}"
  echo -n " SEP "
  ((element++))
done

Quote:

Originally Posted by dazdaz

2. By the following, echo -n " SEP ", do you mean seperator, which is white-space but not necessarily one space.

Yes, but all the code inside the for loop is just for demonstration. Just to echo the results. The actual assignment of the array is simply array=($(cat "testfile")).

burschik · 11-20-2008, 09:40 AM

pwc101 is sure to complain about the useless use of cat in your example.

Code:

array=($(<new))

colucix · 11-20-2008, 09:47 AM

Oh, you're right! I always forget about this syntax. Hope pwc101 does not walk around!

dazdaz · 11-20-2008, 10:19 AM

Thanks for all the posts. When I execute the script I receive the following error :

$ ./array.sh
c6t50060E8010028101d119s2 SEP ./array.sh: ((: element++: syntax error: operand expected (error token is "+")
c6t50060E8010028101d119s2 SEP ./array.sh: ((: element++: syntax error: operand expected (error token is "+")

#!/bin/bash

declare -a array
array=($(cat "/var/tmp/inqraid.out"))

element=0
while [ $element -le $((${#array[@]} - 1)) ]
do
echo -n "${array[$element]}"
echo -n " SEP "
((element++))
done

exit 0

$ bash --version
GNU bash, version 2.03.0(1)-release (sparc-sun-solaris)
Copyright 1998 Free Software Foundation, Inc.

I thought I had done a lot in shell, but shell arrays are all new to me.

colucix · 11-20-2008, 10:33 AM

Well, since you have bash version 2, use

Code:

element=$((element + 1))

instead of ((element++)). Also take a look at the chapter "Arrays" on the Advanced Bash Scripting Guide. A lot of examples there.

ghostdog74 · 11-21-2008, 11:40 AM

Quote:

Originally Posted by dazdaz

1. The only problem is that I don't have the seq command (Solaris 8 and 10).

2. By the following, echo -n " SEP ", do you mean seperator, which is white-space but not necessarily one space.

in Solaris, use nawk. it has much "neater" array syntax, as well as better array capabilities than bash.