Replace Text Between Brackets Using Sed or Awk

awkregular expressionreplacesedtext processing

I'm using awk '{ gsub(/BAR|WIBBLE/, "FOO"); print }' to replace text in data like:

SOMETHING [BAR, WIBBLE]
SOMETHING [BAR]

This gives the desired result of:

SOMETHING [FOO, FOO]
SOMETHING [FOO]

But now I've had to update the text that requires replacing to be something like:

awk '{ gsub(/BAR|WIBBLE|ME/, "FOO"); print }'

Which turns text like:

SOMETHING [ME, WIBBLE]

into:

SOFOOTHING [FOO, FOO]

How can I limit my replacement to just the text between the brackets (i.e. leave the SOMETHING alone)?

EDIT

I also need robustness across whatever text SOMETHING might be (e.g. SHE GAVE ME THAT shouldn't have ME replaced).

Best Answer

Must that be awk? Is much easier in other languages where the substitution's replacement part can be a function call. For example perl:

perl -pe 'sub c{$s=shift;$s=~s/BAR|WIBBLE|ME/FOO/g;$s}s/\[.*?\]/c$&/ge'

Nested Braces

Let's take this as a test file with lots of nested braces:

a{b{c}d}e
1{2
}3{
}
5

Here is a modification to handle nested braces:

$ sed ':again;$!N;$!b again; :b; s/{[^{}]*}//g; t b' file2
ae
13
5

Explanation:

:again;$!N;$!b again

This is the same as before: it reads in the whole file.
:b

This defines a label b.
s/{[^{}]*}//g

This removes text in braces as long as the text contains no inner braces.
t b

If the above substitute command resulted in a change, jump back to label b. In this way, the substitute command is repeated until all brace-groups are removed.

Text Processing – Replace Text Within Curly Brackets Using Sed

Try this:

sed '/CLKA/,/TEST1A/ { s/PortId = \"A/& B/; }' file

This sed command appends the B character to the end of pattern PortId = "A which is between two words CLKA and TEST1A.

Also you can use start(^) and end($) of line notifies to match/replace only PortId = "A" inside the CLKA { ... } module. ^ CLKA {$ matches the line which only contains CLKA { and ^ }$ matches the line if only contains }

Input:

CLKA {
     PortId = "A"
}

 CLKA {    
     Direction = Input
     Tag = Clock
     PortId = "A"
 }

Command:

sed '/^ CLKA {$/,/^ }$/ { s/PortId = \"A/& B/; }' file

Output:

CLKA {
     PortId = "A"
}

 CLKA {    
     Direction = Input
     Tag = Clock
     PortId = "A B"
 }

Note that spaces after ^ because you have a space before each lines(in your given example), if you don't have this space, remove them.

Best Answer

Related Solutions

Text Processing – How to Delete All Text Between Curly Brackets in a Multiline Text File

Nested Braces

Text Processing – Replace Text Within Curly Brackets Using Sed

Input:

Command:

Output:

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