Globally replace text in several files

From Rosetta Code
Task
Globally replace text in several files
You are encouraged to solve this task according to the task description, using any language you may know.
Task

Replace every occurring instance of a piece of text in a group of text files with another one.


For this task we want to replace the text   "Goodbye London!"   with   "Hello New York!"   for a list of files.

Ada[edit]

with Ada.Strings.Unbounded, Ada.Text_IO, Ada.Command_Line, Ada.Directories;
 
procedure Global_Replace is
 
subtype U_String is Ada.Strings.Unbounded.Unbounded_String;
function "+"(S: String) return U_String renames
Ada.Strings.Unbounded.To_Unbounded_String;
function "-"(U: U_String) return String renames
Ada.Strings.Unbounded.To_String;
 
procedure String_Replace(S: in out U_String; Pattern, Replacement: String) is
-- example: if S is "Mary had a XX lamb", then String_Replace(S, "X", "little");
-- will turn S into "Mary had a littlelittle lamb"
-- and String_Replace(S, "Y", "small"); will not change S
 
Index : Natural;
begin
loop
Index := Ada.Strings.Unbounded.Index(Source => S, Pattern => Pattern);
exit when Index = 0;
Ada.Strings.Unbounded.Replace_Slice
(Source => S, Low => Index, High => Index+Pattern'Length-1,
By => Replacement);
end loop;
end String_Replace;
 
procedure File_Replace(Filename: String; Pattern, Replacement: String) is
-- applies String_Rplace to each line in the file with the given Filename
-- propagates any exceptions, when, e.g., the file does not exist
 
I_File, O_File: Ada.Text_IO.File_Type;
Line: U_String;
Tmp_Name: String := Filename & ".tmp";
-- name of temporary file; if that file already exists, it will be overwritten
begin
Ada.Text_IO.Open(I_File, Ada.Text_IO.In_File, Filename);
Ada.Text_IO.Create(O_File, Ada.Text_IO.Out_File, Tmp_Name);
while not Ada.Text_IO.End_Of_File(I_File) loop
Line := +Ada.Text_IO.Get_Line(I_File);
String_Replace(Line, Pattern, Replacement);
Ada.Text_IO.Put_Line(O_File, -Line);
end loop;
Ada.Text_IO.Close(I_File);
Ada.Text_IO.Close(O_File);
Ada.Directories.Delete_File(Filename);
Ada.Directories.Rename(Old_Name => Tmp_Name, New_Name => Filename);
end File_Replace;
 
Pattern: String := Ada.Command_Line.Argument(1);
Replacement: String := Ada.Command_Line.Argument(2);
 
begin
Ada.Text_IO.Put_Line("Replacing """ & Pattern
& """ by """ & Replacement & """ in"
& Integer'Image(Ada.Command_Line.Argument_Count - 2)
& " files.");
for I in 3 .. Ada.Command_Line.Argument_Count loop
File_Replace(Ada.Command_Line.Argument(I), Pattern, Replacement);
end loop;
end Global_Replace;

Ouput:

> ls ?.txt
1.txt  2.txt  x.txt  y.txt

> more 2.txt
This is a text.
"Goodbye London!" 
"Goodbye London!" 
"Byebye London!" "Byebye London!" "Byebye London!" 

> ./global_replace "Goodbye London" "Hello New York" ?.txt
Replacing "Goodbye London" by "Hello New York" in 4 files.

> more 2.txt
This is a text.
"Hello New York!" 
"Hello New York!" 
"Byebye London!" "Byebye London!" "Byebye London!" 

AutoHotkey[edit]

SetWorkingDir %A_ScriptDir%      ; Change the working directory to the script's location
listFiles := "a.txt|b.txt|c.txt" ; Define a list of files in the current working directory
loop, Parse, listFiles, |
{
; The above parses the list based on the | character
fileread, contents, %A_LoopField% ; Read the file
fileDelete, %A_LoopField% ; Delete the file
stringReplace, contents, contents, Goodbye London!, Hello New York!, All ; replace all occurrences
fileAppend, %contents%, %A_LoopField% ; Re-create the file with new contents
}
 

AWK[edit]

 
# syntax: GAWK -f GLOBALLY_REPLACE_TEXT_IN_SEVERAL_FILES.AWK filename(s)
BEGIN {
old_text = "Goodbye London!"
new_text = "Hello New York!"
}
BEGINFILE {
nfiles_in++
text_found = 0
delete arr
}
{ if (gsub(old_text,new_text,$0) > 0) {
text_found++
}
arr[FNR] = $0
}
ENDFILE {
if (text_found > 0) {
nfiles_out++
close(FILENAME)
for (i=1; i<=FNR; i++) {
printf("%s\n",arr[i]) >FILENAME
}
}
}
END {
printf("files: %d read, %d updated\n",nfiles_in,nfiles_out)
exit(0)
}
 
Works with: gawk
@include "readfile"
BEGIN {
while(++i < ARGC)
print gensub("Goodbye London!","Hello New York!","g", readfile(ARGV[i])) > ARGV[i]
}

BASIC[edit]

Works with: FreeBASIC

Pass the files on the command line (i.e. global-replace *.txt).

CONST matchtext = "Goodbye London!"
CONST repltext = "Hello New York!"
CONST matchlen = LEN(matchtext)
 
DIM L0 AS INTEGER, x AS INTEGER, filespec AS STRING, linein AS STRING
 
L0 = 1
WHILE LEN(COMMAND$(L0))
filespec = DIR$(COMMAND$(L0))
WHILE LEN(filespec)
OPEN filespec FOR BINARY AS 1
linein = SPACE$(LOF(1))
GET #1, 1, linein
DO
x = INSTR(linein, matchtext)
IF x THEN
linein = LEFT$(linein, x - 1) & repltext & MID$(linein, x + matchlen)
' If matchtext and repltext are of equal length (as in this example)
' then you can replace the above line with this:
' MID$(linein, x) = repltext
' This is somewhat more efficient than having to rebuild the string.
ELSE
EXIT DO
END IF
LOOP
' If matchtext and repltext are of equal length (as in this example), or repltext
' is longer than matchtext, you could just write back to the file while it's open
' in BINARY mode, like so:
' PUT #1, 1, linein
' But since there's no way to reduce the file size via BINARY and PUT, we do this:
CLOSE
OPEN filespec FOR OUTPUT AS 1
PRINT #1, linein;
CLOSE
filespec = DIR$
WEND
L0 += 1
WEND

BBC BASIC[edit]

      FindThis$ = "Goodbye London!"
ReplaceWith$ = "Hello New York!"
 
DIM Files$(3)
Files$() = "C:\test1.txt", "C:\test2.txt", "C:\test3.txt", "C:\test4.txt"
 
FOR f% = 0 TO DIM(Files$(),1)
infile$ = Files$(f%)
infile% = OPENIN(infile$)
IF infile%=0 ERROR 100, "Failed to open file " + infile$
tmpfile$ = @tmp$+"replace.txt"
tmpfile% = OPENOUT(tmpfile$)
 
WHILE NOT EOF#infile%
INPUT #infile%, a$
IF ASCa$=10 a$ = MID$(a$,2)
l% = LEN(FindThis$)
REPEAT
here% = INSTR(a$, FindThis$)
IF here% a$ = LEFT$(a$,here%-1) + ReplaceWith$ + MID$(a$,here%+l%)
UNTIL here% = 0
PRINT #tmpfile%, a$ : BPUT #tmpfile%,10
ENDWHILE
CLOSE #infile%
CLOSE #tmpfile%
 
OSCLI "DEL """ + infile$ + """"
OSCLI "REN """ + tmpfile$ + """ """ + infile$ + """"
NEXT
END

C[edit]

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <err.h>
#include <string.h>
 
char * find_match(const char *buf, const char * buf_end, const char *pat, size_t len)
{
ptrdiff_t i;
char *start = buf;
while (start + len < buf_end) {
for (i = 0; i < len; i++)
if (start[i] != pat[i]) break;
 
if (i == len) return (char *)start;
start++;
}
return 0;
}
 
int replace(const char *from, const char *to, const char *fname)
{
#define bail(msg) { warn(msg" '%s'", fname); goto done; }
struct stat st;
int ret = 0;
char *buf = 0, *start, *end;
size_t len = strlen(from), nlen = strlen(to);
int fd = open(fname, O_RDWR);
 
if (fd == -1) bail("Can't open");
if (fstat(fd, &st) == -1) bail("Can't stat");
if (!(buf = malloc(st.st_size))) bail("Can't alloc");
if (read(fd, buf, st.st_size) != st.st_size) bail("Bad read");
 
start = buf;
end = find_match(start, buf + st.st_size, from, len);
if (!end) goto done; /* no match found, don't change file */
 
ftruncate(fd, 0);
lseek(fd, 0, 0);
do {
write(fd, start, end - start); /* write content before match */
write(fd, to, nlen); /* write replacement of match */
start = end + len; /* skip to end of match */
/* find match again */
end = find_match(start, buf + st.st_size, from, len);
} while (end);
 
/* write leftover after last match */
if (start < buf + st.st_size)
write(fd, start, buf + st.st_size - start);
 
done:
if (fd != -1) close(fd);
if (buf) free(buf);
return ret;
}
 
int main()
{
const char *from = "Goodbye, London!";
const char *to = "Hello, New York!";
const char * files[] = { "test1.txt", "test2.txt", "test3.txt" };
int i;
 
for (i = 0; i < sizeof(files)/sizeof(char*); i++)
replace(from, to, files[i]);
 
return 0;
}

C++[edit]

#include <fstream>
#include <iterator>
#include <boost/regex.hpp>
#include <string>
#include <iostream>
 
int main( int argc , char *argv[ ] ) {
boost::regex to_be_replaced( "Goodbye London\\s*!" ) ;
std::string replacement( "Hello New York!" ) ;
for ( int i = 1 ; i < argc ; i++ ) {
std::ifstream infile ( argv[ i ] ) ;
if ( infile ) {
std::string filetext( (std::istreambuf_iterator<char>( infile )) ,
std::istreambuf_iterator<char>( ) ) ;
std::string changed ( boost::regex_replace( filetext , to_be_replaced , replacement )) ;
infile.close( ) ;
std::ofstream outfile( argv[ i ] , std::ios_base::out | std::ios_base::trunc ) ;
if ( outfile.is_open( ) ) {
outfile << changed ;
outfile.close( ) ;
}
}
else
std::cout << "Can't find file " << argv[ i ] << " !\n" ;
}
return 0 ;
}

Modern C++ version:

#include <regex>
#include <fstream>
 
using namespace std;
using ist = istreambuf_iterator<char>;
using ost = ostreambuf_iterator<char>;
 
int main(){
auto from = "Goodbye London!", to = "Hello New York!";
for(auto filename : {"a.txt", "b.txt", "c.txt"}) {
ifstream infile {filename};
string content {ist {infile}, ist{}};
infile.close();
ofstream outfile {filename};
regex_replace(ost {outfile}, begin(content), end(content), regex {from}, to);
}
return 0;
}
 

C#[edit]

 
using System.Collections.Generic;
using System.IO;
 
class Program {
static void Main() {
var files = new List<string> {
"test1.txt",
"test2.txt"
};
foreach (string file in files) {
File.WriteAllText(file, File.ReadAllText(file).Replace("Goodbye London!", "Hello New York!"));
}
}
}
 

Clojure[edit]

(defn hello-goodbye [& more]
(doseq [file more]
(spit file (.replace (slurp file) "Goodbye London!" "Hello New York!"))))

Common Lisp[edit]

 
(defun hello-goodbye (files)
(labels ((replace-from-file (file)
(with-open-file (in file)
(loop for line = (read-line in nil)
while line do
(loop for index = (search "Goodbye London!" line)
while index do
(setf (subseq line index) "Hello New York!"))
collecting line)))
(write-lines-to-file (lines file)
(with-open-file (out file :direction :output :if-exists :overwrite)
(dolist (line lines)
(write-line line out))))
(replace-in-file (file)
(write-lines-to-file (replace-from-file file) file)))
(map nil #'replace-in-file files)))
 

D[edit]

Works with: D version 2
import std.file, std.array;
 
void main() {
auto from = "Goodbye London!", to = "Hello, New York!";
foreach (fn; "a.txt b.txt c.txt".split()) {
write(fn, replace(cast(string)read(fn), from, to));
}
}

Erlang[edit]

 
-module( globally_replace_text ).
 
-export( [in_files/3, main/1] ).
 
in_files( Old, New, Files ) when is_list(Old) ->
in_files( binary:list_to_bin(Old), binary:list_to_bin(New), Files );
in_files( Old, New, Files ) -> [replace_in_file(Old, New, X, file:read_file(X)) || X <- Files].
 
main( [Old, New | Files] ) -> in_files( Old, New, Files ).
 
 
 
replace_in_file( Old, New, File, {ok, Binary} ) ->
replace_in_file_return( File, file:write_file(File, binary:replace(Binary, Old, New, [global])) );
replace_in_file( _Old, _New, File, {error, Error} ) ->
io:fwrite( "Error: Could not read ~p: ~p~n", [File, Error] ),
error.
 
replace_in_file_return( _File, ok ) -> ok;
replace_in_file_return( File, {error, Error} ) ->
io:fwrite( "Error: Could not write ~p: ~p~n", [File, Error] ),
error.
 
Output:
macbook-pro:rosettacode bengt$ ls ?.txt
1.txt	2.txt
macbook-pro:rosettacode bengt$ more ?.txt
"Goodbye London!" 
"Goodbye London!" 
"Byebye London!" "Byebye London!" "Byebye London!"
...skipping...
"Goodbye London!" 
"Byebye London!" "Byebye London!" "Byebye London!"
"Goodbye London!"
macbook-pro:rosettacode bengt$ escript globally_replace_text.erl "Goodbye London\!" "Hello New York\!" ?.txt
macbook-pro:rosettacode bengt$ more ?.txt
"Hello New York!" 
"Hello New York!" 
"Byebye London!" "Byebye London!" "Byebye London!"
...skipping...
"Hello New York!" 
"Byebye London!" "Byebye London!" "Byebye London!"
"Hello New York!"

F#[edit]

open System.IO
 
[<EntryPoint>]
let main args =
let textFrom = "Goodbye London!"
let textTo = "Hello New York!"
for name in args do
let content = File.ReadAllText(name)
let newContent = content.Replace(textFrom, textTo)
if content <> newContent then
File.WriteAllText(name, newContent)
0

Fortran[edit]

This is in the style of F77 and solves the usual problem of "how long is a piece of string" by choosing a size that is surely long enough. Thus, CHARACTER*6666 ALINE. Fortran 2003 allows the alteration of the length of a character variable, but, unless there is a facility whereby in something like READ(F,11) ALINE the size of ALINE is adjusted to suit the record being read, this doesn't help much. The Q format code allows discovery of the length of a record as it is being read, and so only the required portion, ALINE(1:L), of an input record is placed and trailing spaces out to 6666 are not supplied nor need they be scanned. Thus an input record that has trailing spaces will have them preserved - unless the text replacement changes spaces...

The search is done by using the supplied INDEX function which alas rarely has an option to specify the starting point via an additional (optional?) parameter. So this must be done via INDEX(ALINE(L1:L),THIS) and then one must carefully consider offsets and the like while counting on fingers and becoming confused. On the other hand, it handles annoyances such as ALINE(L1:L) being shorter than THIS. The expression ALINE(L1:L) does not create a new string variable by copying the specified text, it works (or should work!) via offsets into ALINE. Similarly, there is no attempt to concatenate an output string to write in one go as that too would involve copying text about. Though WRITE statements involve no small overhead in themselves. Although if LEN(THIS) = LEN(THAT) as is the case in the example task an alter-in-place could be used and ALINE(1:L) be written out in one go, the more general approach is used of writing text up to the start of a match, writing out the replacement THAT, and scanning beyond the match for the next text until the tail end.

The file to be altered cannot be changed "in-place", as by writing back an altered record even if the text replacement does not involve a change in length because such a facility is not available for text files that are read and written sequentially only. More accomplished file systems may well offer varying-length records with update possible even of longer or shorter new versions but standard Fortran does not demand such facilities. So, the altered content has to be written to a temporary file (or perhaps could be held in a capacious memory) which is then read back to overwrite the original file. It would be safer to rename the original file and write to a new version, but Fortran typically does not have access to any file renaming facilities and the task calls for an overwrite anyway. So, overwrite it is, which is actually a file delete followed by a write.

Once equipped with a subroutine that applies a specified change to a named disc file, there is no difficulty in invoking it for a horde of disc files. A more civilised routine might make reports about the files assaulted and the number of changes, and also be prepared to report various oddities such as a file being available but not for WRITE. It is for this reason that the source file is opened with READWRITE even though it at that stage is only going to be read from.
      SUBROUTINE FILEHACK(FNAME,THIS,THAT)	!Attacks a file!
CHARACTER*(*) FNAME !The name of the file, presumed to contain text.
CHARACTER*(*) THIS !The text sought in each record.
CHARACTER*(*) THAT !Its replacement, should it be found.
INTEGER F,T !Mnemonics for file unit numbers.
PARAMETER (F=66,T=67) !These should do.
INTEGER L !A length
CHARACTER*6666 ALINE !Surely sufficient?
LOGICAL AHIT !Could count them, but no report is called for.
INQUIRE(FILE = FNAME, EXIST = AHIT) !This mishap is frequent, so attend to it.
IF (.NOT.AHIT) RETURN !Nothing can be done!
OPEN (F,FILE=FNAME,STATUS="OLD",ACTION="READWRITE") !Grab the source file.
OPEN (T,STATUS="SCRATCH") !Request a temporary file.
AHIT = .FALSE. !None found so far.
Chew through the input, replacing THIS by THAT while writing to the temporary file..
10 READ (F,11,END = 20) L,ALINE(1:MIN(L,LEN(ALINE))) !Grab a record.
IF (L.GT.LEN(ALINE)) STOP "Monster record!" !Perhaps unmanageable.
11 FORMAT (Q,A) !Obviously, Q = length of characters unread in the record.
L1 = 1 !Start at the start.
12 L2 = INDEX(ALINE(L1:L),THIS) !Look from L1 onwards.
IF (L2.LE.0) THEN !A hit?
WRITE (T,13) ALINE(L1:L) !No. Finish with the remainder of the line.
13 FORMAT (A) !Thus finishing the output line.
GO TO 10 !And try for the next record.
END IF !So much for not finding THIS.
14 L2 = L1 + L2 - 2 !Otherwise, THIS is found, starting at L1.
WRITE (T,15) ALINE(L1:L2) !So roll the text up to the match, possibly none.
15 FORMAT (A,$) !But not ending the record.
WRITE (T,15) THAT !Because THIS is replaced by THAT.
AHIT = .TRUE. !And we've found at least one match.
L1 = L2 + LEN(THIS) + 1 !Finger the first character beyond the matching THIS.
IF (L - L1 + 1 .GE. LEN(THIS)) GO TO 12 !Might another search succeed?
WRITE (T,13) ALINE(L1:L) !Nope. Finish the line with the tail end.
GO TO 10 !And try for another record.
Copy the temporary file back over the source file. Hope for no mishap and data loss!
20 IF (AHIT) THEN !If there were no hits, there is nothing to do.
CLOSE (F) !Oh well.
REWIND T !Go back to the start.
OPEN (F,FILE="new"//FNAME,STATUS = "REPLACE",ACTION = "WRITE") !Overwrite...
21 READ (T,11,END = 22) L,ALINE(1:MIN(L,LEN(ALINE))) !Grab a line.
IF (L.GT.LEN(ALINE)) STOP "Monster changed record!" !Once you start checking...
WRITE (F,13) ALINE(1:L) !In case LEN(THAT) > LEN(THIS)
GO TO 21 !Go grab the next line.
END IF !So much for the replacement of the file.
22 CLOSE(T) !Finished: it will vanish.
CLOSE(F) !Hopefully, the buffers will be written.
END !So much for that.
 
PROGRAM ATTACK
INTEGER N
PARAMETER (N = 6) !More than one, anyway.
CHARACTER*48 VICTIM(N) !Alternatively, the file names could be read from a file
DATA VICTIM/ !Along with the target and replacement texts in each case.
1 "StaffStory.txt",
2 "Accounts.dat",
3 "TravelAgent.txt",
4 "RemovalFirm.dat",
5 "Addresses.txt",
6 "SongLyrics.txt"/ !Invention flags.
 
DO I = 1,N !So, step through the list.
CALL FILEHACK(VICTIM(I),"Goodbye London!","Hello New York!") !One by one.
END DO !On to the next.
 
END

Go[edit]

package main
 
import (
"bytes"
"io/ioutil"
"log"
"os"
)
 
func main() {
gRepNFiles("Goodbye London!", "Hello New York!", []string{
"a.txt",
"b.txt",
"c.txt",
})
}
 
func gRepNFiles(olds, news string, files []string) {
oldb := []byte(olds)
newb := []byte(news)
for _, fn := range files {
if err := gRepFile(oldb, newb, fn); err != nil {
log.Println(err)
}
}
}
 
func gRepFile(oldb, newb []byte, fn string) (err error) {
var f *os.File
if f, err = os.OpenFile(fn, os.O_RDWR, 0); err != nil {
return
}
defer func() {
if cErr := f.Close(); err == nil {
err = cErr
}
}()
var b []byte
if b, err = ioutil.ReadAll(f); err != nil {
return
}
if bytes.Index(b, oldb) < 0 {
return
}
r := bytes.Replace(b, oldb, newb, -1)
if err = f.Truncate(0); err != nil {
return
}
_, err = f.WriteAt(r, 0)
return
}

Haskell[edit]

The module Data.List provides some useful functions: tails (constructs substrings dropping elements from the head of the list), isPrefixOf (checks if a string matches the beginning of another one) and elemIndices (gets the list indices of all elements matching a value). This code doesn't rewrite the files, it just returns the changes made to the contents of the files.

import Data.List (tails, elemIndices, isPrefixOf)
 
replace :: String -> String -> String -> String
replace [] _ xs = xs
replace _ [] xs = xs
replace _ _ [] = []
replace a b xs = replAll
where
-- make substrings, dropping one element each time
xtails = tails xs
-- what substrings begin with the string to replace?
-- get their indices
matches = elemIndices True $ map (isPrefixOf a) xtails
-- replace one occurrence
repl ys n = take n ys ++ b ++ drop (n + length b) ys
-- replace all occurrences consecutively
replAll = foldl repl xs matches
 
replaceInFiles a1 a2 files = do
f <- mapM readFile files
return $ map (replace a1 a2) f
 

This other version is more effective because it processes the string more lazily, replacing the text as it consumes the input string (the previous version was stricter because of "matches" traversing the whole list; that would force the whole string into memory, which could cause the system to run out of memory with large text files).

replace _ _ [] = []
replace a b xx@(x:xs) =
if isPrefixOf a xx
then b ++ replace a b (drop (length a) xx)
else x : replace a b xs
 

Example:

File "t1.txt" contains: "Goodbye London! This is text 1."
File "t2.txt" contains: "This is text 2. Goodbye London! Now we repeat: Goodbye London! And that's all."

replaceInFiles "Goodbye London!" "Hello New York!" ["t1.txt", "t2.txt"]

Output:

["Hello New York! This is text 1.\n","This is text 2. Hello New York! Now we repeat: Hello New York! And that's all.\n"]

Icon and Unicon[edit]

This example uses the Unicon stat function. It can be rewritten for Icon to aggregate the file in a reads loop.

procedure main()
globalrepl("Goodbye London","Hello New York","a.txt","b.txt") # variable args for files
end
 
procedure globalrepl(old,new,files[])
 
every fn := !files do
if s := reads(f := open(fn,"bu"),stat(f).size) then {
writes(seek(f,1),replace(s,old,new))
close(f)
}
else write(&errout,"Unable to open ",fn)
end
 
link strings # for replace

strings.icn provides replace.

J[edit]

If files is a variable with the desired list of file names:

require'strings'
(1!:2~rplc&('Goodbye London!';'Hello New York!')@(1!:1))"0 files

Java[edit]

Minimalistic version, assumes default encoding.

Works with: Java version 7
import java.io.*;
import java.nio.file.*;
 
public class GloballyReplaceText {
 
public static void main(String[] args) throws IOException {
 
for (String fn : new String[]{"test1.txt", "test2.txt"}) {
String s = new String(Files.readAllBytes(Paths.get(fn)));
s = s.replace("Goodbye London!", "Hello New York!");
try (FileWriter fw = new FileWriter(fn)) {
fw.write(s);
}
}
}
}

Julia[edit]

We will use Julia's built-in Perl-compatible regular-expressions. Although we could read in the files line by line, it is simpler and probably faster to just read the whole file into memory (as text files are likely to fit into memory on modern computers).

filenames = ["f1.txt", "f2.txt"]
for filename in filenames
txt = readall(filename)
open(filename, "w") do f
write(f, replace(txt, "Goodbye London!", "Hello New York!"))
end
end


Lasso[edit]

#!/usr/bin/lasso9
 
local(files = array('f1.txt', 'f2.txt'))
 
with filename in #files
let file = file(#filename)
let content = #file -> readbytes
do {
#file -> dowithclose => {
#content -> replace('Goodbye London!', 'Hello New York!')
#file -> opentruncate
#file -> writebytes(#content)
}
}

Liberty BASIC[edit]

 
nomainwin
 
file$( 1) ="data1.txt"
file$( 2) ="data2.txt"
file$( 3) ="data3.txt"
 
 
for i =1 to 3
open file$( i) for input as #i
orig$ =input$( #i, lof( #i))
close #i
 
dummy$ =FindReplace$( orig$, "Goodbye London!", "Hello New York!", 1)
 
open "RC" +file$( i) for output as #o
#o dummy$;
close #o
next i
 
end
 
function FindReplace$( FindReplace$, find$, replace$, replaceAll)
' Target string, string to find, string to replace it with, flag 0/1 for 'replace all occurrences'.
if ( ( FindReplace$ <>"") and ( find$ <>"") ) then
fLen =len( find$)
rLen =len( replace$)
do
fPos =instr( FindReplace$, find$, fPos)
if not( fPos) then exit function
pre$ =left$( FindReplace$, fPos -1)
post$ =mid$( FindReplace$, fPos +fLen)
FindReplace$ =pre$ +replace$ +post$
fPos =fPos +( rLen -fLen) +1
loop while (replaceAll)
end if
end function
 

Lua[edit]

filenames = { "f1.txt", "f2.txt" }
 
for _, fn in pairs( filenames ) do
fp = io.open( fn, "r" )
str = fp:read( "*all" )
str = string.gsub( str, "Goodbye London!", "Hello New York!" )
fp:close()
 
fp = io.open( fn, "w+" )
fp:write( str )
fp:close()
end


Mathematica / Wolfram Language[edit]

listOfFiles = {"a.txt", "b.txt", "c.txt"};
Do[
filename = listOfFiles[[i]];
filetext = Import[filename, "Text"];
filetext = StringReplace[filetext, "Goodbye London!" -> "Hello New York!"];
Export[filename, filetext, "Text"]
, {i, 1, Length[listOfFiles]}]

File b.txt before the code is run:

second file for the Globally replace text in several files problem. 
Goodbye London! 
Goodbye London!
Bye bye London! 
Bye bye London! Bye bye London!

File b.txt after the code is run:

second file for the Globally replace text in several files problem. 
Hello New York! 
Hello New York!
Bye bye London! 
Bye bye London! Bye bye London!

Nim[edit]

import strutils
 
var fr = "Goodbye London!"
var to = "Hello, New York!"
 
for fn in ["a.txt", "b.txt", "c.txt"]:
fn.writeFile fn.readFile.replace(fr, to)

OpenEdge/Progress[edit]

FUNCTION replaceText RETURNS LOGICAL (
i_cfile_list AS CHAR,
i_cfrom AS CHAR,
i_cto AS CHAR
):
 
DEF VAR ii AS INT.
DEF VAR lcfile AS LONGCHAR.
 
DO ii = 1 TO NUM-ENTRIES( i_cfile_list ):
COPY-LOB FROM FILE ENTRY( ii, i_cfile_list ) TO lcfile.
lcfile = REPLACE( lcfile, i_cfrom, i_cto ).
COPY-LOB FROM lcfile TO FILE ENTRY( ii, i_cfile_list ).
END.
 
END FUNCTION. /* replaceText */
 
replaceText(
"a.txt,b.txt,c.txt",
"Goodbye London!",
"Hello New York!"
).

Pascal[edit]

Works with: Free_Pascal
Program StringReplace;
 
uses
Classes, StrUtils;
 
const
fileName: array[1..3] of string = ('a.txt', 'b.txt', 'c.txt');
matchText = 'Goodbye London!';
replaceText = 'Hello New York!';
 
var
AllText: TStringlist;
i, j: integer;
 
begin
for j := low(fileName) to high(fileName) do
begin
AllText := TStringlist.Create;
AllText.LoadFromFile(fileName[j]);
for i := 0 to AllText.Count-1 do
AllText.Strings[i] := AnsiReplaceStr(AllText.Strings[i], matchText, replaceText);
AllText.SaveToFile(fileName[j]);
AllText.Destroy;
end;
end.

Perl[edit]

perl -pi -e "s/Goodbye London\!/Hello New York\!/g;" a.txt b.txt c.txt

Perl 6[edit]

Current Perl 6 implementations do not yet support the -i flag for editing files in place, so we roll our own (rather unsafe) version:

slurp($_).subst('Goodbye London!', 'Hello New York!', :g) ==> spurt($_)
for <a.txt b.txt c.txt>;

PicoLisp[edit]

(for File '(a.txt b.txt c.txt)
(call 'mv File (tmp File))
(out File
(in (tmp File)
(while (echo "Goodbye London!")
(prin "Hello New York!") ) ) ) )

PowerBASIC[edit]

Translation of: BASIC
$matchtext = "Goodbye London!"
$repltext = "Hello New York!"
 
FUNCTION PBMAIN () AS LONG
DIM L0 AS INTEGER, filespec AS STRING, linein AS STRING
 
L0 = 1
WHILE LEN(COMMAND$(L0))
filespec = DIR$(COMMAND$(L0))
WHILE LEN(filespec)
OPEN filespec FOR BINARY AS 1
linein = SPACE$(LOF(1))
GET #1, 1, linein
' No need to jump through FB's hoops here...
REPLACE $matchtext WITH $repltext IN linein
PUT #1, 1, linein
SETEOF #1
CLOSE
filespec = DIR$
WEND
INCR L0
WEND
END FUNCTION

PowerShell[edit]

 
$listfiles = @('file1.txt','file2.txt')
$old = 'Goodbye London!'
$new = 'Hello New York!'
foreach($file in $listfiles) {
(Get-Content $file).Replace($old,$new) | Set-Content $file
}
 

PureBasic[edit]

Procedure GRTISF(List File$(), Find$, Replace$)
Protected Line$, Out$, OutFile$, i
ForEach File$()
fsize=FileSize(File$())
If fsize<=0: Continue: EndIf
If ReadFile(0, File$())
i=0
;
; generate a temporary file in a safe way
Repeat
file$=GetTemporaryDirectory()+base$+"_"+Str(i)+".tmp"
i+1
Until FileSize(file$)=-1
i=CreateFile(FileID, file$)
If i
; Copy the infile to the outfile while replacing any needed text
While Not Eof(0)
Line$=ReadString(0)
Out$=ReplaceString(Line$,Find$,Replace$)
WriteString(1,Out$)
Wend
CloseFile(1)
EndIf
CloseFile(0)
If i
; If we made a new file, copy it back.
CopyFile(file$, File$())
DeleteFile(file$)
EndIf
EndIf
Next
EndProcedure

Implementation

NewList Xyz$()
AddElement(Xyz$()): Xyz$()="C:\\a.txt"
AddElement(Xyz$()): Xyz$()="C:\\b.txt"
AddElement(Xyz$()): Xyz$()="D:\\c.txt"

GRTISF(Xyz$(), "Goodbye London", "Hello New York")

Python[edit]

From Python docs. (Note: in-place editing does not work for MS-DOS 8+3 filesystems.).

import fileinput
 
for line in fileinput.input(inplace=True):
print(line.replace('Goodbye London!', 'Hello New York!'), end='')
 

Racket[edit]

Code wrapped in a convenient script:

 
#!/usr/bin/env racket
#lang racket
 
(define from-string #f)
(define to-string #f)
 
(command-line
#:once-each
[("-f") from "Text to remove" (set! from-string from)]
[("-t") to "Text to put instead" (set! to-string to)]
#:args files
(unless from-string (error "No `from' string specified"))
(unless to-string (error "No `to' string specified"))
(when (null? files) (error "No files given"))
(define from-rx (regexp (regexp-quote from-string)))
(for ([file files])
(printf "Editing ~a..." file) (flush-output)
(define text1 (file->string file))
(define text2 (regexp-replace* from-rx text1 to-string))
(if (equal? text1 text2)
(printf " no change\n")
(begin (display-to-file text2 file #:exists 'replace)
(printf " modified copy saved in place\n")))))
 

Sample run:

$ ./replace -h
replace [ <option> ... ] [<files>] ...
 where <option> is one of
  -f <from> : Text to remove
  -t <to> : Text to put instead
  --help, -h : Show this help
  -- : Do not treat any remaining argument as a switch (at this level)
 Multiple single-letter switches can be combined after one `-'; for
  example: `-h-' is the same as `-h --'
$ ./replace -f "Goodbye London!" "Hello New York!" file*
Editing file1... no change
Editing file2... modified copy saved in place
Editing file3... modified copy saved in place


REXX[edit]

version 1[edit]

This example works under "DOS" and/or "DOS" under Microsoft Windows.

File names that contain blanks should have their blanks replaced with commas.

/*REXX program  reads  the  files specified  and  globally replaces  a string.          */
old= "Goodbye London!" /*the old text to be replaced. */
new= "Hello New York!" /* " new " used for replacement. */
parse arg fileList /*obtain required list of files from CL*/
files=words(fileList) /*the number of files in the file list.*/
 
do f=1 for files; fn=translate(word(fileList,f),,','); say; say
say '──────── file is being read: ' fn " ("f 'out of' files "files)."
call linein fn,1,0 /*position the file for input. */
changes=0 /*the number of changes in file so far.*/
do rec=0 while lines(fn)\==0 /*read a file (if it exists). */
@.rec=linein(fn) /*read a record (line) from the file. */
if pos(old, @.rec)==0 then iterate /*Anything to change? No, then skip. */
changes=changes + 1 /*flag that file contents have changed.*/
@.rec=changestr(old, @.rec, new) /*change the @.rec record, old ──► new.*/
end /*rec*/
 
say '──────── file has been read: ' fn", with " rec 'records.'
if changes==0 then do; say '──────── file not changed: ' fn; iterate; end
call lineout fn,,1 /*position file for output at 1st line.*/
say '──────── file being changed: ' fn
 
do r=0 for rec; call lineout fn, @.r /*re─write the contents of the file. */
end /*r*/
 
say '──────── file was changed: ' fn " with" changes 'lines changed.'
end /*f*/ /*stick a fork in it, we're all done. */

Some older REXXes don't have a   changestr   BIF,   so one is included here   ──►   CHANGESTR.REX.

output   when using the input (list of files) of:   one.txt   two.txt

──────── file is being read:  one.txt  (1 out of 2 files).
──────── file has been read:  one.txt, with  13 records.
──────── file being changed:  one.txt
──────── file was   changed:  one.txt  with 2 lines changed.


──────── file is being read:  two.txt  (2 out of 2 files).
──────── file has been read:  two.txt, with  59 records.
──────── file being changed:  two.txt
──────── file was   changed:  two.txt  with 6 lines changed.

Version 2[edit]

considering file ids that contain blanks
/* REXX ***************************************************************
* Copy all files *.txt to *.rpl
* replacing all occurrences of old by new
* Execute in the directory containing the files to ne processed
* 16.01.2013 Walter Pachl
* ...if file names contain blanks
**********************************************************************/

Parse Arg a
If a='?' Then Do
Do i=2 To 5
Say substr(sourceline(i),3)
End
Exit
End
'dir *.rpl'
Say 'May I erase *.rpl?'
Parse Upper Pull answer
If answer='Y' | answer='J' Then
'erase *.rpl'
Else Do
Say 'Giving up..'
Exit
End
old='Goodbye London!'
new='Hello New York!'
dir='dir.dir'
'dir *.* >' dir
Do While lines(dir)>0
Parse Value linein(dir) With 37 f
Select
When f='' |,
left(f,1)='.' |,
pos(' Bytes',f)>0 Then Iterate
When right(f,4)='.txt' Then
Call replace
Otherwise
Say left(f,50) 'not eligible for replacing'
End
End
Exit
 
replace:
/* REXX ***************************************************************
* Copy a file fn.txt to fn.rpl
* replacing all occurrences of old by new
**********************************************************************/

oid=fn(f)'.rpl'
cnt.=0
Do ii=1 By 1 While lines(f)>0
l=linein(f)
ol=repl(l,new,old)
Call lineout oid,ol
End
Call lineout f
Call lineout oid
Select
When cnt.0changes=0 Then Do
'erase' oid
Say left(f,50) 'no changes'
End
When cnt.0changes=1 Then
Say left(f,50) '1 change'
Otherwise
Say left(f '->' oid,50) cnt.0changes 'changes'
End
Return
 
fn: Procedure
/* REXX ***************************************************************
* Get the file name of a file id
**********************************************************************/

parse Arg fid
Parse Var fid fn '.' ft
Return fn
 
repl: Procedure Expose cnt.
/* REXX ***************************************************************
* Replace an old string by a new one
**********************************************************************/

Parse Arg s,new,old
ol=''
Do Until p=0
p=pos(old,s)
If p>0 Then Do
ol=ol||left(s,p-1)||new
s=substr(s,p+length(old))
cnt.0changes=cnt.0changes+1
End
Else
ol=ol||s
End
Return ol

Sample output:

 Datenträger in Laufwerk Z: ist H
 Volumeseriennummer: FE17-3A89

 Verzeichnis von Z:\glr

16.01.2013  09:55               283 input.rpl
16.01.2013  09:55               352 input2.rpl
16.01.2013  09:55               283 input file.rpl
               3 Datei(en),            918 Bytes
               0 Verzeichnis(se),  3.993.468.928 Bytes frei
May I erase *.rpl?
  ----> here I entered y
input.txt -> input.rpl                             1 change
input.nix                                          not eligible for replacing
input2.txt -> input2.rpl                           4 changes
dir.dir                                            not eligible for replacing
input file.txt -> input file.rpl                   1 change
input3.txt                                         no changes

Ring[edit]

 
filenames = ["ReadMe.txt", "ReadMe2.txt"]
 
for fn in filenames
fp = fopen(fn,"r")
str = fread(fp,getFileSize(fp))
str = substr(str, "Greetings", "Hello")
fclose(fp)
 
fp = fopen(fn,"w")
fwrite(fp, str)
fclose(fp)
next
 
func getFileSize fp
C_FILESTART = 0
C_FILEEND = 2
fseek(fp,0,C_FILEEND)
nFileSize = ftell(fp)
fseek(fp,0,C_FILESTART)
return nFileSize
 

Ruby[edit]

Like Perl:

ruby -pi -e "gsub('Goodbye London!', 'Hello New York!')" a.txt b.txt c.txt

Run BASIC[edit]

file$(1) ="data1.txt"
file$(2) ="data2.txt"
file$(3) ="data3.txt"
 
for i = 1 to 3
open file$(i) for input as #in
fileBefore$ = input$( #in, lof( #in))
close #in
 
fileAfter$ = strRep$(fileBefore$, "Goodbye London!", "Hello New York!")
open "new_" + file$(i) for output as #out
print #out,fileAfter$;
close #out
next i
end
 
' --------------------------------
' string replace - rep str with
' --------------------------------
FUNCTION strRep$(str$,rep$,with$)
ln = len(rep$)
ln1 = ln - 1
i = 1
while i <= len(str$)
if mid$(str$,i,ln) = rep$ then
strRep$ = strRep$ + with$
i = i + ln1
else
strRep$ = strRep$ + mid$(str$,i,1)
end if
i = i + 1
WEND
END FUNCTION

Sed[edit]

Works with: GNU Sed
sed -i 's/Goodbye London!/Hello New York!/g' a.txt b.txt c.txt

Seed7[edit]

$ include "seed7_05.s7i";
include "getf.s7i";
 
const proc: main is func
local
var string: fileName is "";
var string: content is "";
begin
for fileName range [] ("a.txt", "b.txt", "c.txt") do
content := getf(fileName);
content := replace(content, "Goodbye London!", "Hello New York!");
putf(fileName, content);
end for;
end func;

Sidef[edit]

var files = %w(
a.txt
b.txt
c.txt
);
 
files.map{.to_file}.each { |file|
say file.edit { |line|
line.gsub("Goodbye London!", "Hello New York!");
};
}

Tcl[edit]

Library: Tcllib (Package: fileutil)
package require Tcl 8.5
package require fileutil
 
# Parameters to the replacement
set from "Goodbye London!"
set to "Hello New York!"
# Which files to replace
set fileList [list a.txt b.txt c.txt]
 
# Make a command fragment that performs the replacement on a supplied string
set replacementCmd [list string map [list $from $to]]
# Apply the replacement to the contents of each file
foreach filename $fileList {
fileutil::updateInPlace $filename $replacementCmd
}

TUSCRIPT[edit]

 
$$ MODE TUSCRIPT
files="a.txt'b.txt'c.txt"
 
BUILD S_TABLE search = ":Goodbye London!:"
 
LOOP file=files
ERROR/STOP OPEN (file,WRITE,-std-)
ERROR/STOP CREATE ("scratch",FDF-o,-std-)
ACCESS q: READ/STREAM/RECORDS/UTF8 $file s,aken+text/search+eken
ACCESS s: WRITE/ERASE/STREAM/UTF8 "scratch" s,aken+text+eken
LOOP
READ/EXIT q
IF (text.ct.search) SET text="Hello New York!"
WRITE/ADJUST s
ENDLOOP
ENDACCESS/PRINT q
ENDACCESS/PRINT s
ERROR/STOP COPY ("scratch",file)
ERROR/STOP CLOSE (file)
ENDLOOP
ERROR/STOP DELETE ("scratch")
 

TXR[edit]

Extraction Language[edit]

@(next :args)
@(repeat)
@file
@(next [email protected]`)
@(freeform)
@(coll :gap 0)@notmatch@{match /Goodbye, London!/}@(end)@*tail@/\n/
@(output [email protected]`)
@(rep)@{notmatch}Hello, New York!@(end)@tail
@(end)
@(do @(rename-path [email protected]` file))
@(end)

Run:

$ cat foo.txt
aaaGoodbye, London!aaa
Goodbye, London!
$ cat bar.txt
aaaGoodbye, London!aaa
Goodbye, London!
$ txr replace-files.txr foo.txt bar.txt
$ cat foo.txt
aaaHello, New York!aaa
Hello, New York!
$ cat bar.txt
aaaHello, New York!aaa
Hello, New York!

Run, with no directory permissions:

$ chmod a-w .
$ txr replace-files.txr foo.txt bar.txt
txr: unhandled exception of type file_error:
txr: could not open foo.txt.tmp (error 13/Permission denied)

TXR Lisp[edit]

(each ((fname *args*))
(let* ((infile (open-file fname))
(outfile (open-file [email protected]` "w"))
(content (get-string infile))
(edited (regsub #/Goodbye, London/ "Hello, New York" content)))
(put-string edited outfile)
(rename-path [email protected]` fname)))

UNIX Shell[edit]

Works with: bash
replace() {
local search=$1 replace=$2
local file lines line
shift 2
for file in "$@"; do
lines=()
while IFS= read -r line; do
lines+=( "${line//$search/$replace}" )
done < "$file"
printf "%s\n" "${lines[@]}" > "$file"
done
}
replace "Goodbye London!" "Hello New York!" a.txt b.txt c.txt
Works with: ksh93
function replace {
typeset search=$1 replace=$2
typeset file lines line
shift 2
for file in "$@"; do
lines=()
while IFS= read -r line; do
lines+=( "${line//$search/$replace}" )
done < "$file"
printf "%s\n" "${lines[@]}" > "$file"
done
}
replace "Goodbye London!" "Hello New York!" a.txt b.txt c.txt


VBScript[edit]

Works with: Windows Script Host version *
 
Const ForReading = 1
Const ForWriting = 2
 
strFiles = Array("test1.txt", "test2.txt", "test3.txt")
 
With CreateObject("Scripting.FileSystemObject")
For i = 0 To UBound(strFiles)
strText = .OpenTextFile(strFiles(i), ForReading).ReadAll()
With .OpenTextFile(strFiles(i), ForWriting)
.Write Replace(strText, "Goodbye London!", "Hello New York!")
.Close
End With
Next
End With
 

Vedit macro language[edit]

The list of files is in file "files.lst" which is expected to be in current directory.

File_Open("files.lst")          // list of files to process
#20 = Reg_Free // text register for filename
 
While(!At_EOF) {
Reg_Copy_Block(#20, Cur_Pos, EOL_Pos)
File_Open(@(#20))
Replace("Goodbye London!", "Hello New York!", BEGIN+ALL+NOERR)
Buf_Close(NOMSG)
Line(1, ERRBREAK)
}
 
Reg_Empty(#20) // Cleanup
Buf_Quit(OK)

XPL0[edit]

include c:\cxpl\codes;          \intrinsic 'code' declarations
string 0; \use zero-terminated strings
 
func StrLen(A); \Return number of characters in an ASCIIZ string
char A;
int I;
for I:= 0 to -1>>1-1 do
if A(I) = 0 then return I;
 
func StrFind(A, B); \Search for ASCIIZ string A in string B
\Returns address of first occurrence of string A in B, or zero if A is not found
char A, B; \strings to be compared
int LA, LB, I, J;
[LA:= StrLen(A);
LB:= StrLen(B);
for I:= 0 to LB-LA do
[for J:= 0 to LA-1 do
if A(J) # B(J+I) then J:= LA+1;
if J = LA then return B+I; \found
];
return 0;
];
 
proc ReplaceText(FileName); \replace text in specified file
char FileName;
char Str(1_000_000), Hello, Bye, Pointer;
int Handle, I, C;
[Handle:= FOpen(FileName, 0); \get handle for input file
FSet(Handle, ^I); \set device 3 input to file handle
OpenI(3); \initialize buffer pointers
I:= 0;
repeat C:= ChIn(3); \read file into memory
Str(I):= C;
I:= I+1;
until C = $1A; \EOF
FClose(Handle); \release handle
 
Hello:= "Hello New York!"; \replacement text
Bye:= "Goodbye London!";
Pointer:= StrFind(Bye, Str);
if Pointer \#0\ then \overwrite (both strings are same length)
for I:= 0 to 15-1 do Pointer(I):= Hello(I);
 
Handle:= FOpen(FileName, 1); \get handle for output file
FSet(Handle, ^O); \set device 3 output to file handle
OpenO(3);
I:= 0;
repeat C:= Str(I); \write file from memory
I:= I+1;
ChOut(3, C);
until C = $1A; \EOF
Close(3); \flush output buffer
FClose(Handle); \release handle
];
 
int File, I;
[File:= ["Alpha.txt", "Beta.txt", "Gamma.txt", "Delta.txt"];
for I:= 0 to 4-1 do ReplaceText(File(I));
]

zkl[edit]

fcn sed(data,src,dst){
srcSz:=src.len(); dstSz:=dst.len(); md5:=Utils.MD5.calc(data);
n:=0; while(Void!=(n:=data.find(src,n)))
{ data.del(n,srcSz); data.insert(n,dst); n+= dstSz; }
return(md5!=Utils.MD5.calc(data)); // changed?
}
fcn sedFile(fname,src,dst){
f:=File(fname,"r"); data:=f.read(); f.close();
if(sed(data,"Goodbye London!", "Hello New York!"))
{ f:=File(fname,"w"); f.write(data); f.close(); }
}

This is a read file/blast it/write if changed. You could also do it line by line.

vm.arglist.apply2(sedFile);
$ zkl bbb foo.txt bar.txt

The apply2 method doesn't return anything, it is a side effects method. You could also easily thread this (by using sedFile.launch or sedFile.strand depending on if you wanted a true thread or a co-op thread). I didn't because I didn't want to bother with checking for duplicate files or file locking. vm.arglist, when passed to "main" (the constructor of the file being run) is a copy of argv that has been pruned.