Comments on: Creating associative or hash arrays in bash using sed and strings without the use of arrays, looping and conditionals.

By: Arun Sangal

Arun Sangal — Fri, 15 Apr 2011 21:11:32 +0000

Scripts logic for hashv and hashk funcations in the following lines is wrong in the sense that it’ll not capture all index/values if an index1 string is contained in another index2 string or if value1 string is contained in some other value2 string.

The following line
echo $mh|sed -e “s/.*$[ \t]*$$$hkey$:$[^ \t]*\?$$[ \t]*$.*/\3/gi”

in hashv() should be changed to:
echo $mhash | sed “s/ /\n/g”| grep “^${hkey}:” | cut -d’:’ -f2

AND

The following line
echo $mh|grep “$hvalue”|sed -e “s/$[^ \t]*$[:]$$hvalue$/\|\1|\2\|/i” -e “s/.*\?[|]$.*$[|].*[|].*\?/\1/i”;

in hashk () should be changed to:
echo $mhash | sed “s/ /\n/g”| grep “:${hvalue}$” | cut -d’:’ -f1

Then, with any set of index:value pair i.e. a:1 or aa:11 or ab:2 abab:23 or cd:2323 will work correctly.

By: Arun K Sangal

Arun K Sangal — Fri, 15 Apr 2011 20:24:38 +0000

OK..corrected the logic for hash array. Now the below script will run like a 1969 pony ass. It’s showing “55″ now for abcd index …and also not worrying about “eabcd” index (as this index contains “abcd” in the string). See the comment in script for “^” and “$” characters usage in grep.

[user@BS001 stage]$ cat ./gigahash.sh
#!/bin/bash

mhash=”abcd:55 bcda:4422 cdab:321 dabc:2131 eabcd:11 giga:aks”;

function hashv {
hkey=”";
mh=”";
if [[ $2 != "" ]]; then hkey=$2; else echo “”; return 0; fi
if [[ $1 != "" ]]; then mh=$1; else echo “”; return 0; fi

## Note the placement of “^” character in grep.
echo $mh | sed “s/ /\n/g”| grep “^${hkey}” | cut -d’:’ -f2
}

function hashk {
hvalue=”";
mh=”";
if [[ $2 != "" ]]; then hvalue=$2; else echo “”; return 0; fi
if [[ $1 != "" ]]; then mh=$1; else echo “”; return 0; fi

## Note the placement of “$” character in grep.
echo $mh | sed “s/ /\n/g”| grep ${hvalue}$| cut -d’:’ -f1
}

echo “____________________________________”;
hashv “$mhash” “eabcd”;
hashk “$mhash” “11″;
echo “____________________________________”;
hashv “$mhash” “”;
hashk “” “11″;
echo “____________________________________”;
hashv “$mhash” “bcda”;
hashk “$mhash” “4422″;
echo “____________________________________”;
hashv “$mhash” “abcd”;
hashk “$mhash” “2131″;
echo “____________________________________”;
hashv “$mhash” “cdab”;
hashk “$mhash” “55″;
echo “____________________________________”;

[user@BS001 stage]$ ./gigahash.sh
____________________________________
11
eabcd
____________________________________

____________________________________
4422
bcda
____________________________________
55
dabc
____________________________________
321
abcd
____________________________________
[user@BS001 stage]$

By: Arun Sangal

Arun Sangal — Fri, 15 Apr 2011 19:44:31 +0000

The above didn’t work for the following example:

[user@BS001 stage]$ cat gigahash.sh
#!/bin/bash

mhash=”abcd:55 bcda:4422 cdab:321 dabc:2131 eabcd:11″;

function hashv {
hkey=”";
mh=”";
if [[ $2 != "" ]]; then hkey=$2; else echo “”; return 0; fi
if [[ $1 != "" ]]; then mh=$1; else echo “”; return 0; fi

echo $mh|sed -e “s/.*$[ \t]*$$$hkey$:$[^ \t]*\?$$[ \t]*$.*/\3/gi”
}

function hashk {
hvalue=”";
mh=”";
if [[ $2 != "" ]]; then hvalue=$2; else echo “”; return 0; fi
if [[ $1 != "" ]]; then mh=$1; else echo “”; return 0; fi

echo $mh|grep “$hvalue”|sed -e “s/$[^ \t]*$[:]$$hvalue$/\|\1|\2\|/i” -e “s/.*\?[|]$.*$[|].*[|].*\?/\1/i”;
}

[user@BS001 stage]$

Now when I run the above script, “11″ in
“11
dabc
” is wrong. i.e. “hashv “$mhash” “abcd”;” failed to print the correct value of 55.. it printed 11 (which is for eabcd hash key’s value). Looks like a little tweak to the above funcations would correct it.

[user@BS001 stage]$ ./gigahash.sh
____________________________________
11
eabcd
____________________________________

____________________________________
4422
bcda
____________________________________
11
dabc
____________________________________
321
abcd
____________________________________
[user@BS001 stage]$

By: BASH, HASH and AWK - The UNIX and Linux Forums

BASH, HASH and AWK - The UNIX and Linux Forums — Sun, 07 Feb 2010 11:52:53 +0000

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