myFunction (line0

line1

line2

line3

line4)

myFunction ( )

$ awk '$0~/[(]/,$0~/[)]/{gsub(/line/,"newline")};1' input.txt
another line
something else

myFunction (newline0

newline1

whatever

newline2

newline3

newline4)

some other line

$ cat input.txt
another line
something else

myFunction (line0

line1

lilne2

line3

line4)

some other line
$ ./edit_function_args.py input.txt
another line
something else

myFunction (newline0

newline1

newline2

newline3

line4)

some other line

#!/bin/bash
# Use shell builtins, read, true, false, printf
flag=false
while IFS= read -r line
do
    case "$line" in
    (*"("*) flag=true ;;
    esac

    if $flag
    then
        line=${line//line/newline}
    fi

    printf "%sn" "$line"

    case "$line" in
    (*")"*) flag=false ;;
    esac

done < "$1"

$ perl -0777 -pe 's/([^)]+)/$&=~s|line|newline|gr/ge' ip.txt
myFunction (newline0

newline1

newline2

newline3

newline4)

sed '/(/,/)/s/line/newline/g'

sed -e '/(/{' -e ':loop;s/(.*)/()/;t;N;b loop' -e '}'

sed -e '/(/{
:loop
s/(.*)/()/
t
N
b loop
}'

awk '
  function mysub(str) {
    if (str) gsub(/line/, "newline", str); return str
  }
  BEGIN {
    OFS=FS="("
  }
  NF>1 {
    if (FS=="(") {
      print $1,mysub($2); OFS=FS=")"
    } else {
      print mysub($1),$2; OFS=FS="("
    }
    next
  }
  {
    print FS=="(" ? $0 : mysub($0)
  }' /path/to/input

awk 'function m(s){gsub(/line/,"newline",s);return s}BEGIN{OFS=FS="("}NF>1{if(FS=="("){print $1,m($2);OFS=FS=")"}else{print m($1),$2;OFS=FS="("}next}{print FS=="("?$0:m($0)}' /path/to/input

line96
line97 myFunction (line0

line1

line2

line3

line4) line98
line99

line96
line97 myFunction (newline0

newline1

newline2

newline3

newline4) line98
line99

awk '
  BEGIN {
    OFS=FS="("
  }
  NF>1 {
    if (FS=="(") {
      print $1,""; OFS=FS=")"
    } else {
      print "",$2; OFS=FS="("
    }
    next
  }
  FS=="("' /path/to/input

line96
line97 myFunction (
) line98
line99

$ cat d.txt
myOtherFunction (x as boolean
y as integer
d as string
e as whatever)

myFunction (xx as boolean
yy as integer
dd as string
ee as whatever)

$ cat d2.txt
BrandNewFunction (xxx as integer
yyy as boolean
ddd as integer
eee as whatever)

$ a="$(sed -n '/myFunction (/,/)/p' d.txt)" #isolates myFunction from the source file d.txt
$ b="$(cat d2.txt)" #get contents of file d2.txt (BrandNewFunction)
$ c="$(cat d.txt)" #get the whole source file d.txt
$ echo "${c/$a/$b}" #in source file d.txt ($c) replace $a with $b (d2.txt)
#Output:
myOtherFunction (x as boolean
y as integer
d as string
e as whatever)

BrandNewFunction (xxx as integer
yyy as boolean
ddd as integer
eee as whatever)

$ a="$(sed -n '/myFunction (/,/)/p' d.txt)";b="$(cat d2.txt)";c="$(cat d.txt)";echo "${c/$a/$b}"

$ b="$(sed -n '/BrandNewFunction (/,/)/p' d2.txt)"

$ b="myFunction ( )"

sgrep -o '%r ' '(start .. end) extracting ("("__")")' < input_file

myFunction (line0

line1

(line2)

line3

line4)

anotherFun (x y)

myFunction ( )

anotherFun ( )

sed -z 's/([^)]*)/( )/g' inputfile