Using a grep that knows about -o:

$ printf '%s\n' "$string" | grep -o '\<Icecream[^[:blank:]]*'
Icecream123

The pattern \<Icecream[^[:blank:]]* matches the string Icecream (where the I is preceded by a non-word character, or the start of the line) followed by zero or more non-blanks (not spaces or tabs).

Using awk:

$ printf '%s\n' "$string" | awk -v RS=' ' '/^Icecream/'       
Icecream123

The awk program divides the string into space-separated records, and tests each one. It will print the ones that start with the string Icecream.

Using mawk or GNU awk, you may also use

printf '%s\n' "$string" | awk -v RS='[[:blank:]]' '/^Icecream/'

since they interpet RS as a regular expression if it contains more than one character.

With sed, in a similar fashion as with grep:

$ printf '%s\n' "$string" | sed 's/.*\(\<Icecream[^[:blank:]]*\).*/\1/'
Icecream123

Using /bin/sh:

set -- Icecream123 AirplaneBCD CompanyTL1 ComputerYU1
for string; do
    case $string in
        Icecream*)
            printf '%s\n' "$string"
            break
    esac
done

Using a grep that knows about -o:

$ printf '%s\n' "$string" | grep -o '\<Icecream[^[:blank:]]*'
Icecream123

The pattern \<Icecream[^[:blank:]]* matches the string Icecream (where the I is preceded by a non-word character, or the start of the line) followed by zero or more non-blanks (not spaces or tabs).

Using awk:

$ printf '%s\n' "$string" | awk -v RS=' ' '/^Icecream/'       
Icecream123

The awk program divides the string into space-separated records, and tests each one. It will print the ones that start with the string Icecream.

Using mawk or GNU awk, you may also use

printf '%s\n' "$string" | awk -v RS='[[:blank:]]' '/^Icecream/'

since they interpet RS as a regular expression if it contains more than one character.

With sed, in a similar fashion as with grep:

$ printf '%s\n' "$string" | sed 's/.*\(\<Icecream[^[:blank:]]*\).*/\1/'
Icecream123

Using /bin/sh:

set -- Icecream123 AirplaneBCD CompanyTL1 ComputerYU1
for string; do
    case $string in
        Icecream*)
            printf '%s\n' "$string"
            break
    esac
done

Perl (with a little help from tr):

$ printf '%s\n' "$string" | tr ' ' '\n' | perl -ne '/Icecream\S*/ && print'
Icecream123

or just

$ printf '%s\n' "$string" | perl -ne '/(Icecream\S*)/ && print $1, "\n"'
Icecream123

Using a grep that knows about -o:

$ printf '%s\n' "$string" | grep -o '\<Icecream[^[:blank:]]*'
Icecream123

The pattern \<Icecream[^[:blank:]]* matches the string Icecream (where the I is preceded by a non-word character) followed by zero or more non-blanks (not spaces nor tabs).

Using awk:

$ printf '%s\n' "$string" | awk -v RS=' ' '/^Icecream/'       
Icecream123

The awk program divides the string into space-separated records, and tests each one. It will print the ones that start with the string Icecream.

With sed, in a similar fashion as with grep:

$ printf '%s\n' "$string" | sed 's/.*\(\<Icecream[^[:blank:]]*\).*/\1/'
Icecream123

Using a grep that knows about -o:

$ printf '%s\n' "$string" | grep -o '\<Icecream[^[:blank:]]*'
Icecream123

The pattern \<Icecream[^[:blank:]]* matches the string Icecream (where the I is preceded by a non-word character, or the start of the line) followed by zero or more non-blanks (not spaces or tabs).

Using awk:

$ printf '%s\n' "$string" | awk -v RS=' ' '/^Icecream/'       
Icecream123

The awk program divides the string into space-separated records, and tests each one. It will print the ones that start with the string Icecream.

Using mawk or GNU awk, you may also use

printf '%s\n' "$string" | awk -v RS='[[:blank:]]' '/^Icecream/'

since they interpet RS as a regular expression if it contains more than one character.

With sed, in a similar fashion as with grep:

$ printf '%s\n' "$string" | sed 's/.*\(\<Icecream[^[:blank:]]*\).*/\1/'
Icecream123

Using /bin/sh:

set -- Icecream123 AirplaneBCD CompanyTL1 ComputerYU1
for string; do
    case $string in
        Icecream*)
            printf '%s\n' "$string"
            break
    esac
done