CODEWITHSUNDEEP
linuxshellunix
Androidz
Androidz

Reputation: 401

Unix - how to use cut -d on one word

I have a string with two words but sometimes it may contain only one word and i need to get both words and if the second one is empty i want an empty string. I am using the following:

STRING1=`echo $STRING|cut -d' ' -f1`
STRING2=`echo $STRING|cut -d' ' -f2`

When STRING is only one word both strings are equal but I need the second screen to be empty.

Upvotes: 1

Views: 22928

Answers (3)

anubhava
anubhava

Reputation: 785196

Why not just use read:

STR='word1 word2'
read string1 string2 <<< "$STR"
echo "$string1"
word1
echo "$string2"
word2

Now the missing 2nd word:

STR='word1'
read string1 string2 <<< "$STR"
echo "$string1"
word1
echo "$string2" | cat -vte
$

Upvotes: 1

tripleee
tripleee

Reputation: 189427

The shell has built-in functionality for this.

echo "First word: ${STRING%% *}"
echo "Last word: ${STRING##* }"

The double ## or %% is not compatible with older shells; they only had a single-separator variant, which trims the shortest possible match instead of the longest. (You can simulate longest suffix by extracting the shortest prefix, then trim everything else, but this takes two trims.)

Mnemonic: # is to the left of $ on the keyboard, % is to the right.

For your actual problem, I would add a simple check to see if the first extraction extracted the whole string; if so, the second should be left empty.

STRING1="${STRING%% *}"
case $STRING1 in
    "$STRING" ) STRING2="" ;;
    * ) STRING2="${STRING#$STRING1 }" ;;
esac

As an aside, there's also this:

set $STRING
STRING1=$1
STRING2=$2

Upvotes: 2

M.E.L.
M.E.L.

Reputation: 613

Your problem is (from cut(1))

`-f FIELD-LIST'
`--fields=FIELD-LIST'
   Select for printing only the fields listed in FIELD-LIST.  Fields
   are separated by a TAB character by default.  Also print any line
   that contains no delimiter character, unless the
   `--only-delimited' (`-s') option is specified.

You could specify -s when extracing the second word, or use

echo " $STRING" | cut -d' ' -f3

to extract the second word (note the fake separator in front of $STRING).

Upvotes: 6

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