Replacing strings in files based on certain search criteria is a very common task. How can I
foo with bar in all files in the current directory?These are for cases where you know that the directory contains only regular files and that you want to process all non-hidden files. If that is not the case, use the approaches in 2.
All sed solutions in this answer assume GNU sed. If using FreeBSD or macOS, replace -i with -i ''. Also note that the use of the -i switch with any version of sed has certain filesystem security implications and is inadvisable in any script which you plan to distribute in any way.
Non recursive, files in this directory only:
sed -i -- 's/foo/bar/g' *
perl -i -pe 's/foo/bar/g' ./*
(the perl one will fail for file names ending in | or space)).
Recursive, regular files (including hidden ones) in this and all subdirectories
find . -type f -exec sed -i 's/foo/bar/g' {} +
If you are using zsh:
sed -i -- 's/foo/bar/g' **/*(D.)
(may fail if the list is too big, see zargs to work around).
Bash can't check directly for regular files, a loop is needed (braces avoid setting the options globally):
( shopt -s globstar dotglob;
for file in **; do
if [[ -f $file ]] && [[ -w $file ]]; then
sed -i -- 's/foo/bar/g' "$file"
fi
done
)
The files are selected when they are actual files (-f) and they are writable (-w).
Non-recursive, files in this directory only:
sed -i -- 's/foo/bar/g' *baz* ## all files whose name contains baz
sed -i -- 's/foo/bar/g' *.baz ## files ending in .baz
Recursive, regular files in this and all subdirectories
find . -type f -name "*baz*" -exec sed -i 's/foo/bar/g' {} +
If you are using bash (braces avoid setting the options globally):
( shopt -s globstar dotglob
sed -i -- 's/foo/bar/g' **baz*
sed -i -- 's/foo/bar/g' **.baz
)
If you are using zsh:
sed -i -- 's/foo/bar/g' **/*baz*(D.)
sed -i -- 's/foo/bar/g' **/*.baz(D.)
The -- serves to tell sed that no more flags will be given in the command line. This is useful to protect against file names starting with -.
If a file is of a certain type, for example, executable (see man find for more options):
find . -type f -executable -exec sed -i 's/foo/bar/g' {} +
zsh:
sed -i -- 's/foo/bar/g' **/*(D*)
Replace foo with bar only if there is a baz later on the same line:
sed -i 's/foo\(.*baz\)/bar\1/' file
In sed, using \( \) saves whatever is in the parentheses and you can then access it with \1. There are many variations of this theme, to learn more about such regular expressions, see here.
Replace foo with bar only if foo is found on the 3d column (field) of the input file (assuming whitespace-separated fields):
gawk -i inplace '{gsub(/foo/,"baz",$3); print}' file
(needs gawk 4.1.0 or newer).
For a different field just use $N where N is the number of the field of interest. For a different field separator (: in this example) use:
gawk -i inplace -F':' '{gsub(/foo/,"baz",$3);print}' file
Another solution using perl:
perl -i -ane '$F[2]=~s/foo/baz/g; $" = " "; print "@F\n"' foo
NOTE: both the awk and perl solutions will affect spacing in the file (remove the leading and trailing blanks, and convert sequences of blanks to one space character in those lines that match). For a different field, use $F[N-1] where N is the field number you want and for a different field separator use (the $"=":" sets the output field separator to :):
perl -i -F':' -ane '$F[2]=~s/foo/baz/g; $"=":";print "@F"' foo
Replace foo with bar only on the 4th line:
sed -i '4s/foo/bar/g' file
gawk -i inplace 'NR==4{gsub(/foo/,"baz")};1' file
perl -i -pe 's/foo/bar/g if $.==4' file
You can combine sed commands:
sed -i 's/foo/bar/g; s/baz/zab/g; s/Alice/Joan/g' file
Be aware that order matters (sed 's/foo/bar/g; s/bar/baz/g' will substitute foo with baz).
or Perl commands
perl -i -pe 's/foo/bar/g; s/baz/zab/g; s/Alice/Joan/g' file
If you have a large number of patterns, it is easier to save your patterns and their replacements in a sed script file:
#! /usr/bin/sed -f
s/foo/bar/g
s/baz/zab/g
Or, if you have too many pattern pairs for the above to be feasible, you can read pattern pairs from a file (two space separated patterns, $pattern and $replacement, per line):
while read -r pattern replacement; do
sed -i "s/$pattern/$replacement/" file
done < patterns.txt
That will be quite slow for long lists of patterns and large data files so you might want to read the patterns and create a sed script from them instead. The following assumes a <<!>space<!>> delimiter separates a list of MATCH<<!>space<!>>REPLACE pairs occurring one-per-line in the file patterns.txt :
sed 's| *\([^ ]*\) *\([^ ]*\).*|s/\1/\2/g|' <patterns.txt |
sed -f- ./editfile >outfile
The above format is largely arbitrary and, for example, doesn't allow for a <<!>space<!>> in either of MATCH or REPLACE. The method is very general though: basically, if you can create an output stream which looks like a sed script, then you can source that stream as a sed script by specifying sed's script file as -stdin.
You can combine and concatenate multiple scripts in similar fashion:
SOME_PIPELINE |
sed -e'#some expression script' \
-f./script_file -f- \
-e'#more inline expressions' \
./actual_edit_file >./outfile
A POSIX sed will concatenate all scripts into one in the order they appear on the command-line. None of these need end in a \newline.
grep can work the same way:
sed -e'#generate a pattern list' <in |
grep -f- ./grepped_file
When working with fixed-strings as patterns, it is good practice to escape regular expression metacharacters. You can do this rather easily:
sed 's/[]$&^*\./[]/\\&/g
s| *\([^ ]*\) *\([^ ]*\).*|s/\1/\2/g|
' <patterns.txt |
sed -f- ./editfile >outfile
Replace any of foo, bar or baz with foobar
sed -Ei 's/foo|bar|baz/foobar/g' file
or
perl -i -pe 's/foo|bar|baz/foobar/g' file
Another use case of using different delimiter:
sed -i 's|path/to/foo|path/to/bar|g' *
A good replacement Linux tool is rpl, that was originally written for the Debian project, so it is available with apt-get install rpl in any Debian derived distro, and may be for others, but otherwise you can download the tar.gz file from SourceForge.
Simplest example of use:
$ rpl old_string new_string test.txt
Note that if the string contains spaces it should be enclosed in quotation marks. By default rpl takes care of capital letters but not of complete words, but you can change these defaults with options -i (ignore case) and -w (whole words). You can also specify multiple files:
$ rpl -i -w "old string" "new string" test.txt test2.txt
Or even specify the extensions (-x) to search or even search recursively (-R) in the directory:
$ rpl -x .html -x .txt -R old_string new_string test*
You can also search/replace in interactive mode with -p (prompt) option:
The output shows the numbers of files/string replaced and the type of search (case in/sensitive, whole/partial words), but it can be silent with the -q (quiet mode) option, or even more verbose, listing line numbers that contain matches of each file and directory with -v (verbose mode) option.
Other options that are worth remembering are -e (honor escapes) that allow regular expressions, so you can search also tabs (\t), new lines (\n),etc. You can use -f to force permissions (of course, only when the user has write permissions) and -d to preserve the modification times`).
Finally, if you are unsure what exactly will happen, use the -s (simulate mode).
How to do a search and replace over multiple files suggests:
You could also use find and sed, but I find that this little line of perl works nicely.
perl -pi -w -e 's/search/replace/g;' *.php
- -e means execute the following line of code.
- -i means edit in-place
- -w write warnings
- -p loop over the input file, printing each line after the script is applied to it.
My best results come from using perl and grep (to ensure that file have the search expression )
perl -pi -w -e 's/search/replace/g;' $( grep -rl 'search' )
I used this:
grep -r "old_string" -l | tr '\n' ' ' | xargs sed -i 's/old_string/new_string/g'
List all files that contain old_string.
Replace newline in result with spaces (so that the list of files can be fed to sed.
Run sed on those files to replace old string with new.
Update: The above result will fail on filenames that contain whitespaces. Instead, use:
grep --null -lr "old_string" | xargs --null sed -i 's/old_string/new_string/g'
You can use Vim in Ex mode:
replace string ALF with BRA in all files in the current directory?
for CHA in *
do
ex -sc '%s/ALF/BRA/g' -cx "$CHA"
done
do the same recursively for sub directories?
find -type f -exec ex -sc '%s/ALF/BRA/g' -cx {} ';'
replace only if the file name matches another string?
for CHA in *.txt
do
ex -sc '%s/ALF/BRA/g' -cx "$CHA"
done
replace only if the string is found in a certain context?
ex -sc 'g/DEL/s/ALF/BRA/g' -cx file
replace if the string is on a certain line number?
ex -sc '2s/ALF/BRA/g' -cx file
replace multiple strings with the same replacement
ex -sc '%s/\vALF|ECH/BRA/g' -cx file
replace multiple strings with different replacements
ex -sc '%s/ALF/BRA/g|%s/FOX/GOL/g' -cx file
From a user's perspective, a nice & simple Unix tool that does the job perfectly is qsubst. For example,
% qsubst foo bar *.c *.h
will replace foo with bar in all my C files. A nice feature is that qsubst will do a query-replace, i.e., it will show me each occurrence of foo and ask whether I want to replace it or not. [You can replace unconditionally (no asking) with -go option, and there are other options, e.g., -w if you only want to replace foo when it is a whole word.]
How to get it: qsubst was invented by der Mouse (from McGill) and posted to comp.unix.sources 11(7) in Aug. 1987. Updated versions exist. For example, the NetBSD version qsubst.c,v 1.8 2004/11/01 compiles and runs perfectly on my mac.
ripgrep (command name rg) is a grep tool, but supports search and replace as well.
$ cat ip.txt
dark blue and light blue
light orange
blue sky
$ # by default, line number is displayed if output destination is stdout
$ # by default, only lines that matched the given pattern is displayed
$ # 'blue' is search pattern and -r 'red' is replacement string
$ rg 'blue' -r 'red' ip.txt
1:dark red and light red
3:red sky
$ # --passthru option is useful to print all lines, whether or not it matched
$ # -N will disable line number prefix
$ # this command is similar to: sed 's/blue/red/g' ip.txt
$ rg --passthru -N 'blue' -r 'red' ip.txt
dark red and light red
light orange
red sky
rg doesn't support in-place option, so you'll have to do it yourself
$ # -N isn't needed here as output destination is a file
$ rg --passthru 'blue' -r 'red' ip.txt > tmp.txt && mv tmp.txt ip.txt
$ cat ip.txt
dark red and light red
light orange
red sky
See Rust regex documentation for regular expression syntax and features. The -P switch will enable PCRE2 flavor. rg supports Unicode by default.
$ # non-greedy quantifier is supported
$ echo 'food land bark sand band cue combat' | rg 'foo.*?ba' -r 'X'
Xrk sand band cue combat
$ # unicode support
$ echo 'fox:αλεπού,eagle:αετός' | rg '\p{L}+' -r '($0)'
(fox):(αλεπού),(eagle):(αετός)
$ # set operator example, remove all punctuation characters except . ! and ?
$ para='"Hi", there! How *are* you? All fine here.'
$ echo "$para" | rg '[[:punct:]--[.!?]]+' -r ''
Hi there! How are you? All fine here.
$ # use -P if you need even more advanced features
$ echo 'car bat cod map' | rg -P '(bat|map)(*SKIP)(*F)|\w+' -r '[$0]'
[car] bat [cod] map
Like grep, the -F option will allow fixed strings to be matched, a handy option which I feel sed should implement too.
$ printf '2.3/[4]*6\nfoo\n5.3-[4]*9\n' | rg --passthru -F '[4]*' -r '2'
2.3/26
foo
5.3-29
Another handy option is -U which enables multiline matching
$ # (?s) flag will allow . to match newline characters as well
$ printf '42\nHi there\nHave a Nice Day' | rg --passthru -U '(?s)the.*ice' -r ''
42
Hi Day
rg can handle dos-style files too
$ # same as: sed -E 's/\w+(\r?)$/123\1/'
$ printf 'hi there\r\ngood day\r\n' | rg --passthru --crlf '\w+$' -r '123'
hi 123
good 123
Another advantage of rg is that it is likely to be faster than sed
$ # for small files, initial processing time of rg is a large component
$ time echo 'aba' | sed 's/a/b/g' > f1
real 0m0.002s
$ time echo 'aba' | rg --passthru 'a' -r 'b' > f2
real 0m0.007s
$ # for larger files, rg is likely to be faster
$ # 6.2M sample ASCII file
$ wget https://norvig.com/big.txt
$ time LC_ALL=C sed 's/\bcat\b/dog/g' big.txt > f1
real 0m0.060s
$ time rg --passthru '\bcat\b' -r 'dog' big.txt > f2
real 0m0.048s
$ diff -s f1 f2
Files f1 and f2 are identical
$ time LC_ALL=C sed -E 's/\b(\w+)(\s+\1)+\b/\1/g' big.txt > f1
real 0m0.725s
$ time rg --no-unicode --passthru -wP '(\w+)(\s+\1)+' -r '$1' big.txt > f2
real 0m0.093s
$ diff -s f1 f2
Files f1 and f2 are identical
I needed something that would provide a dry-run option and would work recursively with a glob, and after trying to do it with awk and sed I gave up and instead did it in python.
The script searches recursively all files matching a glob pattern (e.g. --glob="*.html") for a regex and replaces with the replacement regex:
find_replace.py [--dir=my_folder] \
--search-regex=<search_regex> \
--replace-regex=<replace_regex> \
--glob=[glob_pattern] \
--dry-run
Every long option such as --search-regex has a corresponding short option, i.e. -s. Run with -h to see all options.
For example, this will flip all dates from 2017-12-31 to 31-12-2017:
python replace.py --glob=myfile.txt \
--search-regex="(\d{4})-(\d{2})-(\d{2})" \
--replace-regex="\3-\2-\1" \
--dry-run --verbose
import os
import fnmatch
import sys
import shutil
import re
import argparse
def find_replace(cfg):
search_pattern = re.compile(cfg.search_regex)
if cfg.dry_run:
print('THIS IS A DRY RUN -- NO FILES WILL BE CHANGED!')
for path, dirs, files in os.walk(os.path.abspath(cfg.dir)):
for filename in fnmatch.filter(files, cfg.glob):
if cfg.print_parent_folder:
pardir = os.path.normpath(os.path.join(path, '..'))
pardir = os.path.split(pardir)[-1]
print('[%s]' % pardir)
filepath = os.path.join(path, filename)
# backup original file
if cfg.create_backup:
backup_path = filepath + '.bak'
while os.path.exists(backup_path):
backup_path += '.bak'
print('DBG: creating backup', backup_path)
shutil.copyfile(filepath, backup_path)
with open(filepath) as f:
old_text = f.read()
all_matches = search_pattern.findall(old_text)
if all_matches:
print('Found {} matches in file {}'.format(len(all_matches), filename))
new_text = search_pattern.sub(cfg.replace_regex, old_text)
if not cfg.dry_run:
with open(filepath, "w") as f:
print('DBG: replacing in file', filepath)
f.write(new_text)
else:
for idx, matches in enumerate(all_matches):
print("Match #{}: {}".format(idx, matches))
print("NEW TEXT:\n{}".format(new_text))
elif cfg.verbose:
print('File {} does not contain search regex "{}"'.format(filename, cfg.search_regex))
if __name__ == '__main__':
parser = argparse.ArgumentParser(description='''DESCRIPTION:
Find and replace recursively from the given folder using regular expressions''',
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog='''USAGE:
{0} -d [my_folder] -s <search_regex> -r <replace_regex> -g [glob_pattern]
'''.format(os.path.basename(sys.argv[0])))
parser.add_argument('--dir', '-d',
help='folder to search in; by default current folder',
default='.')
parser.add_argument('--search-regex', '-s',
help='search regex',
required=True)
parser.add_argument('--replace-regex', '-r',
help='replacement regex',
required=True)
parser.add_argument('--glob', '-g',
help='glob pattern, i.e. *.html',
default="*.*")
parser.add_argument('--dry-run', '-dr',
action='store_true',
help="don't replace anything just show what is going to be done",
default=False)
parser.add_argument('--create-backup', '-b',
action='store_true',
help='Create backup files',
default=False)
parser.add_argument('--verbose', '-v',
action='store_true',
help="Show files which don't match the search regex",
default=False)
parser.add_argument('--print-parent-folder', '-p',
action='store_true',
help="Show the parent info for debug",
default=False)
config = parser.parse_args(sys.argv[1:])
find_replace(config)
Hereis an updated version of the script which highlights the search terms and replacements with different colors.
Update July 2022: I have a really robust wrapper tool, rgr, which stands for "RipGrep Replace" and which wraps the incredibly fast RipGrep tool (rg), which you should use instead. See my other answer here. My wrapper supports all rg options, while adding -R for actual, on-disk text replacements.
Here I use grep to tell if it is going to change a file (so I can count the number of lines changed, and replacements made, to output at the end), then I use sed to actually change the file. Notice the single line of sed usage at the very end of the Bash function below:
replace_str Bash functionUpdate: the below code has been upgraded and is now part of my eRCaGuy_dotfiles project as "find_and_replace.sh" here. <-- I recommend you use this tool now instead.
Usage:
gs_replace_str "regex_search_pattern" "replacement_string" "file_path"
Bash Function:
# Usage: `gs_replace_str "regex_search_pattern" "replacement_string" "file_path"`
gs_replace_str() {
REGEX_SEARCH="$1"
REPLACEMENT_STR="$2"
FILENAME="$3"
num_lines_matched=$(grep -c -E "$REGEX_SEARCH" "$FILENAME")
# Count number of matches, NOT lines (`grep -c` counts lines),
# in case there are multiple matches per line; see:
# https://superuser.com/questions/339522/counting-total-number-of-matches-with-grep-instead-of-just-how-many-lines-match/339523#339523
num_matches=$(grep -o -E "$REGEX_SEARCH" "$FILENAME" | wc -l)
# If num_matches > 0
if [ "$num_matches" -gt 0 ]; then
echo -e "\n${num_matches} matches found on ${num_lines_matched} lines in file"\
"\"${FILENAME}\":"
# Now show these exact matches with their corresponding line 'n'umbers in the file
grep -n --color=always -E "$REGEX_SEARCH" "$FILENAME"
# Now actually DO the string replacing on the files 'i'n place using the `sed`
# 's'tream 'ed'itor!
sed -i "s|${REGEX_SEARCH}|${REPLACEMENT_STR}|g" "$FILENAME"
fi
}
Place that in your ~/.bashrc file, for instance. Close and reopen your terminal and then use it.
Replace do with bo so that "doing" becomes "boing" (I know, we should be fixing spelling errors not creating them :) ):
$ gs_replace_str "do" "bo" test_folder/test2.txt
9 matches found on 6 lines in file "test_folder/test2.txt":
1:hey how are you doing today
2:hey how are you doing today
3:hey how are you doing today
4:hey how are you doing today hey how are you doing today hey how are you doing today hey how are you doing today
5:hey how are you doing today
6:hey how are you doing today?
$SHLVL:3
Screenshot of the output, to show the matched text being highlighted in red:
My RipGrep Replace wrapper, rgr, is now my go-to on-disk find-and-replace and grep-replacement tool, period. It is incredibly robust, fast, and thorough. Unlike grep, it handles a full feature-set of regular expression syntax. It is 0.348s/0.136s = ~3x faster than git grep, and 0.806s/0.136s = ~6x faster than GNU grep (see RipGrep speed tests here), and rgr supports on-disk find-and-replace!
My rgr wrapper around the incredibly fast RipGrep (rg) tool gives it the ability to do on-disk textual replacements via a new -R option. I call my wrapper rgr, for "RipGrep Replace", since it will do the find-and-replace feature on your disk via the -R option I added.
See the installation instructions at the top of rg_replace.sh, so you can use it as rgr.
For additional information on it, see my comments here and here.
Example usages as shown from the help menu, accessed via rgr -h or rgr --help, are here:
EXAMPLE USAGES:
rgr foo -r boo
Do a *dry run* to replace all instances of 'foo' with 'boo' in this folder and down.
rgr foo -R boo
ACTUALLY REPLACE ON YOUR DISK all instances of 'foo' with 'boo' in this folder and down.
rgr foo -R boo file1.c file2.c file3.c
Same as above, but only in these 3 files.
rgr foo -R boo -g '*.txt'
Use a glob filter to replace on your disk all instances of 'foo' with 'boo' in .txt files
ONLY, inside this folder and down. Learn more about RipGrep's glob feature here:
https://github.com/BurntSushi/ripgrep/blob/master/GUIDE.md#manual-filtering-globs
rgr foo -R boo --stats
Replace on your disk all instances of 'foo' with 'boo', showing detailed statistics.
See the rgr --help menu yourself for a full description.