find & replace only exact match between delimiters in string values-CodePudding

I have a string value stored in a variable:

PTYPE="Other Farm|Raised Ranch|Farm house|Other|A-Frame|Log Home"

I want to find & replace Other with some value like NOTHING. All values are stored in variables.

WhatToChange=Other
NewValue=NOTHING

echo $PTYPE|sed -e "s@${WhatToChange}@${NewValue}@g"

This is replacing all the occurances of Other and getting output like:

NOTHING Farm|Raised Ranch|Farm house|NOTHING|A-Frame|Log Home

Is there any way I can exactly change only the exact one? The place for ${WhatToChange} is variable.

CodePudding user response：

To match either the exact character | or the beginning of the line, use ([|]|^).

To match either the exact character | or the end of the line, use ([|]|$).

To put a | back in place only when appropriate, store these in match groups, and refer to those groups with \1 or \2:

PTYPE="Other Farm|Raised Ranch|Farm house|Other|A-Frame|Log Home"
WhatToChange=Other
NewValue=NOTHING

sed -re "s@(^|[|])${WhatToChange}($|[|])@\1${NewValue}\2@g" <<<"$PTYPE"

...emits as output:

Other Farm|Raised Ranch|Farm house|NOTHING|A-Frame|Log Home

...and still works even if WhatToChange is matched at the beginning or end of the list.

CodePudding user response：

As you have well defined fields and want an exact match, awk could be easier to use than sed; at the very least, you won't have to worry about escaping the strings for using it in the sed expression:

echo "Other Farm|Raised Ranch|Farm house|Other|A-Frame|Log Home" |
awk -v old="Other" -v new="NOTHING" \
    'BEGIN {FS = OFS = "|"} {for(i=1;i<=NF;i  ) if($i == old) $i = new} 1'

output:

Other Farm|Raised Ranch|Farm house|NOTHING|A-Frame|Log Home

CodePudding user response：

For fun, some perl:

This is like @Charles's sed solution: Note the \Q...\E so that the "to change" value is treated as literal text.

echo "$PTYPE" | perl -spe '
    s{ (?:^|\|)\K \Q$WhatToChange\E (?=\||$) }{$NewValue}gx
' -- -WhatToChange=Other -NewValue=NOTHING

This is like @Fravadona's awk solution:

echo "$PTYPE" | perl -F'[|]' -sane '
    print join "|", map {$_ eq $WhatToChange ? $NewValue : $_} @F
' -- -WhatToChange=Other -NewValue=NOTHING