[SOLVED] Count a position of word in variable

pedropt · 02-21-2020, 03:50 PM

on this code

Quote:

var="aaa bbb ccc ddd eeee"

how can i know that bbb is the 2nd word in variable ?

thanks

petelq · 02-21-2020, 04:10 PM

Make the variable an array and then each group of letters becomes 0,1,2,3,4 in the array. Look up arrays in your bash tutorial. It's pretty staightforward.

pedropt · 02-21-2020, 04:52 PM

An array does not work for what i need because that variable is just an example .

teckk · 02-21-2020, 05:11 PM

Quote:

how can i know that bbb is the 2nd word in variable ?

It isn't. That is one variable. There are not multiple words in that.

You can parse it though.

Code:

var="aaa bbb ccc ddd eeee"

echo "$var"
aaa bbb ccc ddd eeee

echo "$var" | cut -d ' ' -f1
aaa

echo "$var" | cut -d ' ' -f2
bbb

echo "${var:4:3}"
bbb

Make an array

Code:

a=(aaa bbb ccc ddd eee)

echo "${a[@]}"
aaa bbb ccc ddd eee

for i in {0..5}; do
    echo "${a[$i]}"
done

aaa
bbb
ccc
ddd
eee

Post what you are trying to accomplish.

SoftSprocket · 02-21-2020, 05:13 PM

If you split the string on spaces and then compare the resulting strings in an indexed loop you will have the answer.

pedropt · 02-21-2020, 05:34 PM

Again , an array does not work for what i need .
That example is just an example , in reality that var will come with a lot of values that may or not appear depending on what user writes in terminal , and will also appear other values that i have to pick.

1st , forget array , one solution would be using tr according to SoftSprocket.

Code:

var="aaa bbb ccc ddd eee"
a1=$(echo "$var" | tr " " "\n" > tmp.file)
a2=$(grep -n "bbb" tmp.file | sed 's/[:].*$//'
)
echo "bbb is the number $a2 word"

However i will have a problem ahead , witch is :
bbb may not exist in variable but i have to look for it , and if i look for something that does not exist with grep and the -n switch then i will have an error .

pedropt · 02-21-2020, 07:55 PM

Well i found a way to deal with this issue .
Was using tr as i did before but with a few changes along the code that it makes no importance to post here , since my last code solves this issue .

MadeInGermany · 02-22-2020, 02:20 AM

Code:

var="aaa bbb ccc ddd eee"
search="bbb"
a2=$(echo "$var" |
  tr -s " " "\n" |
  sed "/^$search\$/="
)
if [ -n "$a2" ]
then
  echo "$search is the number $a2 word"
else
  echo "$search not found"
fi

The a2 can be set as well with shell builtins:

Code:

a2=$(
  cnt=0
  set -f
  for word in $var
  do
    ((cnt+=1))
    if [ "$search" = "$word" ]
    then
      echo "$cnt"
      break
    fi
  done
)

As you see, the $( ) is a complete sub-shell.
It makes sense to put such lengthy code into a function, especially if you plan to use it several times.

petelq · 02-22-2020, 04:46 AM

Quote:

Originally Posted by pedropt

An array does not work for what i need because that variable is just an example .

You should have given us a better example because an array certainly would work with the example you gave.

boughtonp · 02-22-2020, 06:29 PM

Quote:

Originally Posted by pedropt

1st , forget array , one solution would be using tr according to SoftSprocket.

Code:

var="aaa bbb ccc ddd eee"
a1=$(echo "$var" | tr " " "\n" > tmp.file)
a2=$(grep -n "bbb" tmp.file | sed 's/[:].*$//'
)
echo "bbb is the number $a2 word"

Simpler version of same thing:

Code:

var="aaa bbb ccc ddd eee"
a2=$(echo "$var" | tr " " "\n" | grep -n "bbb" | sed 's/:.*//')
echo "bbb is the number $a2 word"

but...

Quote:

However i will have a problem ahead , witch is :
bbb may not exist in variable but i have to look for it , and if i look for something that does not exist with grep and the -n switch then i will have an error .

You also have two other problems highlighted by var="aaa bbbb ccc bbb ddd eee bbb"

It's frustrating that no equivalent to ListFind(haystack,needle,delimiter) is provided natively by any CLI-based languages. Here's a quick Python implementation:

Code:

import sys;
  
try:
   haystack = sys.argv[1]
   needle = sys.argv[2]
   delim = sys.argv[3] if len(sys.argv) > 3 else " "
   pos = haystack.split(delim).index(needle)+1;
except:
   pos = 0;

print(pos)

It returns the first match, or zero if no matches:

Code:

$ python listfind.py "aaa bbb ccc ddd eeee" "bbb"
2
$ python listfind.py "aaa bbbb ccc bbb ddd eeee bbb" "bbb"
4
$ python listfind.py "aaa bbb ccc ddd eeee" "qqq"
0

danielbmartin · 02-23-2020, 01:33 PM

Quote:

Originally Posted by pedropt

on this code

how can i know that bbb is the 2nd word in variable ?

thanks

Please clarify. Do you want a Yes/No answer to this question or a position number such as 0=not found, 2=found in second position?

Daniel B. Martin

.

danielbmartin · 02-24-2020, 09:57 AM

A solution for your consideration. No arrays. No loops.
Handles the "not found" case.

This program ...

Code:

#!/bin/bash   Daniel B. Martin   Feb20  

# To execute this program, launch a terminal session and enter:
#   bash /home/daniel/Desktop/LQfiles/dbm2152.bin
#
# This program inspired by ...
# https://www.linuxquestions.org/questions/programming-9/
#  count-a-position-of-word-in-variable-4175670031/

# var="aaa bbb ccc ddd eeee"
# how can i know that bbb is the 2nd word in variable ?
 
# Keywords: word position

# File identification
      Path=${0%%.*}
   OutFile=$Path"out.txt"

function WordPos () {
local n=$(cut -d " " -f1 <<<$*)  # n=needle
WordPos=$(tr " " "\n" <<<$* \
|nl -nln -v0                \
|grep -wm2 $n               \
|tail -n1                   \
|cut -d' ' -f1)
# The position of the needle in the haystack
#   is in the global variable WordPos.
# WordPos=0 means the needle was not found.
}  # End of function WordPos


haystack="aaa bbb ccc ddd eeee"

echo; echo "Example #1 of LQ Member danielbmartin."
needle="bbb"
echo 'Find this needle '$needle
echo '  in this haystack '$haystack
WordPos $needle $haystack
echo 'WordPos='$WordPos

echo; echo "Example #2 of LQ Member danielbmartin."
needle="cc"
echo 'Find this needle '$needle
echo '  in this haystack '$haystack
WordPos $needle $haystack
echo 'WordPos='$WordPos

echo; echo "Normal end of job."; echo; exit

... produced this result ...

Code:

Example #1 of LQ Member danielbmartin.
Find this needle bbb
  in this haystack aaa bbb ccc ddd eeee
WordPos=2

Example #2 of LQ Member danielbmartin.
Find this needle cc
  in this haystack aaa bbb ccc ddd eeee
WordPos=0

Normal end of job.

As always, corrections and constructive criticisms are invited.

Daniel B. Martin

.

SoftSprocket · 02-24-2020, 11:39 AM

I don't do any bash programming these days but it seems to me something like this would work:

Code:

#!/bin/bash


IFS=' ' read -ra splits <<< "$1"

searchStr="$2"
res=""

for i in "${!splits[@]}"; do
        if [ "${splits[$i]}" == "${searchStr}" ]; then
                res="$res$i "
        fi
done

printf "${res}\n"

Code:

$ ./position_in_string.sh "aaa bbb ccc bbbb bbb" "bbb"
1 4

Zero indexed of course.