Related
What's the simplest way to do a find and replace for a given input string, say abc, and replace with another string, say XYZ in file /tmp/file.txt?
I am writting an app and using IronPython to execute commands through SSH — but I don't know Unix that well and don't know what to look for.
I have heard that Bash, apart from being a command line interface, can be a very powerful scripting language. So, if this is true, I assume you can perform actions like these.
Can I do it with bash, and what's the simplest (one line) script to achieve my goal?
The easiest way is to use sed (or perl):
sed -i -e 's/abc/XYZ/g' /tmp/file.txt
Which will invoke sed to do an in-place edit due to the -i option. This can be called from bash.
If you really really want to use just bash, then the following can work:
while IFS='' read -r a; do
echo "${a//abc/XYZ}"
done < /tmp/file.txt > /tmp/file.txt.t
mv /tmp/file.txt{.t,}
This loops over each line, doing a substitution, and writing to a temporary file (don't want to clobber the input). The move at the end just moves temporary to the original name. (For robustness and security, the temporary file name should not be static or predictable, but let's not go there.)
For Mac users:
sed -i '' 's/abc/XYZ/g' /tmp/file.txt
(See the comment below why)
File manipulation isn't normally done by Bash, but by programs invoked by Bash, e.g.:
perl -pi -e 's/abc/XYZ/g' /tmp/file.txt
The -i flag tells it to do an in-place replacement.
See man perlrun for more details, including how to take a backup of the original file.
I was surprised when I stumbled over this...
There is a replace command which ships with the "mysql-server" package, so if you have installed it try it out:
# replace string abc to XYZ in files
replace "abc" "XYZ" -- file.txt file2.txt file3.txt
# or pipe an echo to replace
echo "abcdef" |replace "abc" "XYZ"
See man replace for more on this.
This is an old post but for anyone wanting to use variables as #centurian said the single quotes mean nothing will be expanded.
A simple way to get variables in is to do string concatenation since this is done by juxtaposition in bash the following should work:
sed -i -e "s/$var1/$var2/g" /tmp/file.txt
Bash, like other shells, is just a tool for coordinating other commands. Typically you would try to use standard UNIX commands, but you can of course use Bash to invoke anything, including your own compiled programs, other shell scripts, Python and Perl scripts etc.
In this case, there are a couple of ways to do it.
If you want to read a file, and write it to another file, doing search/replace as you go, use sed:
sed 's/abc/XYZ/g' <infile >outfile
If you want to edit the file in place (as if opening the file in an editor, editing it, then saving it) supply instructions to the line editor 'ex'
echo "%s/abc/XYZ/g
w
q
" | ex file
Example is like vi without the fullscreen mode. You can give it the same commands you would at vi's : prompt.
I found this thread among others and I agree it contains the most complete answers so I'm adding mine too:
sed and ed are so useful...by hand.
Look at this code from #Johnny:
sed -i -e 's/abc/XYZ/g' /tmp/file.txt
When my restriction is to use it in a shell script, no variable can be used inside in place of "abc" or "XYZ". The BashFAQ seems to agree with what I understand at least. So, I can't use:
x='abc'
y='XYZ'
sed -i -e 's/$x/$y/g' /tmp/file.txt
#or,
sed -i -e "s/$x/$y/g" /tmp/file.txt
but, what can we do? As, #Johnny said use a while read... but, unfortunately that's not the end of the story. The following worked well with me:
#edit user's virtual domain
result=
#if nullglob is set then, unset it temporarily
is_nullglob=$( shopt -s | egrep -i '*nullglob' )
if [[ is_nullglob ]]; then
shopt -u nullglob
fi
while IFS= read -r line; do
line="${line//'<servername>'/$server}"
line="${line//'<serveralias>'/$alias}"
line="${line//'<user>'/$user}"
line="${line//'<group>'/$group}"
result="$result""$line"'\n'
done < $tmp
echo -e $result > $tmp
#if nullglob was set then, re-enable it
if [[ is_nullglob ]]; then
shopt -s nullglob
fi
#move user's virtual domain to Apache 2 domain directory
......
As one can see if nullglob is set then, it behaves strangely when there is a string containing a * as in:
<VirtualHost *:80>
ServerName www.example.com
which becomes
<VirtualHost ServerName www.example.com
there is no ending angle bracket and Apache2 can't even load.
This kind of parsing should be slower than one-hit search and replace but, as you already saw, there are four variables for four different search patterns working out of one parse cycle.
The most suitable solution I can think of with the given assumptions of the problem.
You can use sed:
sed -i 's/abc/XYZ/gi' /tmp/file.txt
You can use find and sed if you don't know your filename:
find ./ -type f -exec sed -i 's/abc/XYZ/gi' {} \;
Find and replace in all Python files:
find ./ -iname "*.py" -type f -exec sed -i 's/abc/XYZ/gi' {} \;
Be careful if you replace URLs with "/" character.
An example of how to do it:
sed -i "s%http://domain.com%http://www.domain.com/folder/%g" "test.txt"
Extracted from: http://www.sysadmit.com/2015/07/linux-reemplazar-texto-en-archivos-con-sed.html
If the file you are working on is not so big, and temporarily storing it in a variable is no problem, then you can use Bash string substitution on the whole file at once - there's no need to go over it line by line:
file_contents=$(</tmp/file.txt)
echo "${file_contents//abc/XYZ}" > /tmp/file.txt
The whole file contents will be treated as one long string, including linebreaks.
XYZ can be a variable eg $replacement, and one advantage of not using sed here is that you need not be concerned that the search or replace string might contain the sed pattern delimiter character (usually, but not necessarily, /). A disadvantage is not being able to use regular expressions or any of sed's more sophisticated operations.
You may also use the ed command to do in-file search and replace:
# delete all lines matching foobar
ed -s test.txt <<< $'g/foobar/d\nw'
See more in "Editing files via scripts with ed".
To edit text in the file non-interactively, you need in-place text editor such as vim.
Here is simple example how to use it from the command line:
vim -esnc '%s/foo/bar/g|:wq' file.txt
This is equivalent to #slim answer of ex editor which is basically the same thing.
Here are few ex practical examples.
Replacing text foo with bar in the file:
ex -s +%s/foo/bar/ge -cwq file.txt
Removing trailing whitespaces for multiple files:
ex +'bufdo!%s/\s\+$//e' -cxa *.txt
Troubleshooting (when terminal is stuck):
Add -V1 param to show verbose messages.
Force quit by: -cwq!.
See also:
How to edit files non-interactively (e.g. in pipeline)? at Vi SE
Try the following shell command:
find ./ -type f -name "file*.txt" | xargs sed -i -e 's/abc/xyz/g'
You can use python within the bash script too. I didn't have much success with some of the top answers here, and found this to work without the need for loops:
#!/bin/bash
python
filetosearch = '/home/ubuntu/ip_table.txt'
texttoreplace = 'tcp443'
texttoinsert = 'udp1194'
s = open(filetosearch).read()
s = s.replace(texttoreplace, texttoinsert)
f = open(filetosearch, 'w')
f.write(s)
f.close()
quit()
Simplest way to replace multiple text in a file using sed command
Command -
sed -i 's#a/b/c#D/E#g;s#/x/y/z#D:/X#g;' filename
In the above command s#a/b/c#D/E#g where I am replacing a/b/c with D/E and then after the ; we again doing the same thing
You can use rpl command. For example you want to change domain name in whole php project.
rpl -ivRpd -x'.php' 'old.domain.name' 'new.domain.name' ./path_to_your_project_folder/
This is not clear bash of cause, but it's a very quick and usefull. :)
For MAC users in case you don't read the comments :)
As mentioned by #Austin, if you get the Invalid command code error
For the in-place replacements BSD sed requires a file extension after the -i flag to save to a backup file with given extension.
sed -i '.bak' 's/find/replace' /file.txt
You can use '' empty string if you want to skip backup.
sed -i '' 's/find/replace' /file.txt
All merit to #Austin
Open file using vim editor. In command mode
:%s/abc/xyz/g
This is the simplest
In case of doing changes in multiple files together we can do in a single line as:-
user_name='whoami'
for file in file1.txt file2.txt file3.txt; do sed -i -e 's/default_user/${user_name}/g' $file; done
Added if in case could be useful.
I have to implement an application in shell programming (Unix/Linux).
I have to search a word from a text file and replace that word with my given word. I have a knowledge on shell and still learning.
I am not expecting source code. Can anybody help me or suggest me or give me some similar solution....
cat abc.txt | grep "pattern" | sed 's/"pattern"/"new pattern"/g'
The above command should work
Thanks,
Regards,
Dheeraj Rampally
Say you are looking for pattern in a file (input.txt) and want to replace it with "new pattern" in another (output.txt)
Here is the main idea, without UUOC:
<input.txt sed 's/"pattern"/"new pattern"/g' >output.txt
todo
Now you need to embed this line in your program. You may want to make it interactive, or a command that you could use with 3 parameters.
edit
I tried to avoid the use of output.txt as a temporary file with this:
<input.txt sed 's/"pattern"/"new pattern"/g' >input.txt
but it empties input.txt for a reason I can't understand. So I tried with a subshell, so:
echo $(<input.txt sed 's/pattern/"new pattern"/g')>input.txt
... but the echo command removes line breaks... still looking.
edit2
From https://unix.stackexchange.com/questions/11067/is-there-a-way-to-modify-a-file-in-place , it looks like writing to the very same file at once it not easy at all. However, I could do what I wanted with sed -i for linux only:
sed -i 's/pattern/"new pattern"/g' input.txt
From sed -i + what the same option in SOLARIS , it looks like there's no alternative, and you must use a temporary file:
sed 's/pattern/"new pattern"/g' input.txt > input.tmp && mv input.tmp input.txt
I have a text file which has a particular line something like
sometext sometext sometext TEXT_TO_BE_REPLACED sometext sometext sometext
I need to replace the whole line above with
This line is removed by the admin.
The search keyword is TEXT_TO_BE_REPLACED
I need to write a shell script for this. How can I achieve this using sed?
You can use the change command to replace the entire line, and the -i flag to make the changes in-place. For example, using GNU sed:
sed -i '/TEXT_TO_BE_REPLACED/c\This line is removed by the admin.' /tmp/foo
You need to use wildcards (.*) before and after to replace the whole line:
sed 's/.*TEXT_TO_BE_REPLACED.*/This line is removed by the admin./'
The Answer above:
sed -i '/TEXT_TO_BE_REPLACED/c\This line is removed by the admin.' /tmp/foo
Works fine if the replacement string/line is not a variable.
The issue is that on Redhat 5 the \ after the c escapes the $. A double \\ did not work either (at least on Redhat 5).
Through hit and trial, I discovered that the \ after the c is redundant if your replacement string/line is only a single line. So I did not use \ after the c, used a variable as a single replacement line and it was joy.
The code would look something like:
sed -i "/TEXT_TO_BE_REPLACED/c $REPLACEMENT_TEXT_STRING" /tmp/foo
Note the use of double quotes instead of single quotes.
The accepted answer did not work for me for several reasons:
my version of sed does not like -i with a zero length extension
the syntax of the c\ command is weird and I couldn't get it to work
I didn't realize some of my issues are coming from unescaped slashes
So here is the solution I came up with which I think should work for most cases:
function escape_slashes {
sed 's/\//\\\//g'
}
function change_line {
local OLD_LINE_PATTERN=$1; shift
local NEW_LINE=$1; shift
local FILE=$1
local NEW=$(echo "${NEW_LINE}" | escape_slashes)
# FIX: No space after the option i.
sed -i.bak '/'"${OLD_LINE_PATTERN}"'/s/.*/'"${NEW}"'/' "${FILE}"
mv "${FILE}.bak" /tmp/
}
So the sample usage to fix the problem posed:
change_line "TEXT_TO_BE_REPLACED" "This line is removed by the admin." yourFile
All of the answers provided so far assume that you know something about the text to be replaced which makes sense, since that's what the OP asked. I'm providing an answer that assumes you know nothing about the text to be replaced and that there may be a separate line in the file with the same or similar content that you do not want to be replaced. Furthermore, I'm assuming you know the line number of the line to be replaced.
The following examples demonstrate the removing or changing of text by specific line numbers:
# replace line 17 with some replacement text and make changes in file (-i switch)
# the "-i" switch indicates that we want to change the file. Leave it out if you'd
# just like to see the potential changes output to the terminal window.
# "17s" indicates that we're searching line 17
# ".*" indicates that we want to change the text of the entire line
# "REPLACEMENT-TEXT" is the new text to put on that line
# "PATH-TO-FILE" tells us what file to operate on
sed -i '17s/.*/REPLACEMENT-TEXT/' PATH-TO-FILE
# replace specific text on line 3
sed -i '3s/TEXT-TO-REPLACE/REPLACEMENT-TEXT/'
for manipulation of config files
i came up with this solution inspired by skensell answer
configLine [searchPattern] [replaceLine] [filePath]
it will:
create the file if not exists
replace the whole line (all lines) where searchPattern matched
add replaceLine on the end of the file if pattern was not found
Function:
function configLine {
local OLD_LINE_PATTERN=$1; shift
local NEW_LINE=$1; shift
local FILE=$1
local NEW=$(echo "${NEW_LINE}" | sed 's/\//\\\//g')
touch "${FILE}"
sed -i '/'"${OLD_LINE_PATTERN}"'/{s/.*/'"${NEW}"'/;h};${x;/./{x;q100};x}' "${FILE}"
if [[ $? -ne 100 ]] && [[ ${NEW_LINE} != '' ]]
then
echo "${NEW_LINE}" >> "${FILE}"
fi
}
the crazy exit status magic comes from https://stackoverflow.com/a/12145797/1262663
In my makefile I use this:
#sed -i '/.*Revision:.*/c\'"`svn info -R main.cpp | awk '/^Rev/'`"'' README.md
PS: DO NOT forget that the -i changes actually the text in the file... so if the pattern you defined as "Revision" will change, you will also change the pattern to replace.
Example output:
Abc-Project written by John Doe
Revision: 1190
So if you set the pattern "Revision: 1190" it's obviously not the same as you defined them as "Revision:" only...
bash-4.1$ new_db_host="DB_HOSTNAME=good replaced with 122.334.567.90"
bash-4.1$
bash-4.1$ sed -i "/DB_HOST/c $new_db_host" test4sed
vim test4sed
'
'
'
DB_HOSTNAME=good replaced with 122.334.567.90
'
it works fine
To do this without relying on any GNUisms such as -i without a parameter or c without a linebreak:
sed '/TEXT_TO_BE_REPLACED/c\
This line is removed by the admin.
' infile > tmpfile && mv tmpfile infile
In this (POSIX compliant) form of the command
c\
text
text can consist of one or multiple lines, and linebreaks that should become part of the replacement have to be escaped:
c\
line1\
line2
s/x/y/
where s/x/y/ is a new sed command after the pattern space has been replaced by the two lines
line1
line2
cat find_replace | while read pattern replacement ; do
sed -i "/${pattern}/c ${replacement}" file
done
find_replace file contains 2 columns, c1 with pattern to match, c2 with replacement, the sed loop replaces each line conatining one of the pattern of variable 1
To replace whole line containing a specified string with the content of that line
Text file:
Row: 0 last_time_contacted=0, display_name=Mozart, _id=100, phonebook_bucket_alt=2
Row: 1 last_time_contacted=0, display_name=Bach, _id=101, phonebook_bucket_alt=2
Single string:
$ sed 's/.* display_name=\([[:alpha:]]\+\).*/\1/'
output:
100
101
Multiple strings delimited by white-space:
$ sed 's/.* display_name=\([[:alpha:]]\+\).* _id=\([[:digit:]]\+\).*/\1 \2/'
output:
Mozart 100
Bach 101
Adjust regex to meet your needs
[:alpha] and [:digit:]
are Character Classes and Bracket Expressions
This worked for me:
sed -i <extension> 's/.*<Line to be replaced>.*/<New line to be added>/'
An example is:
sed -i .bak -e '7s/.*version.*/ version = "4.33.0"/'
-i: The extension for the backup file after the replacement. In this case, it is .bak.
-e: The sed script. In this case, it is '7s/.*version.*/ version = "4.33.0"/'. If you want to use a sed file use the -f flag
s: The line number in the file to be replaced. In this case, it is 7s which means line 7.
Note:
If you want to do a recursive find and replace with sed then you can grep to the beginning of the command:
grep -rl --exclude-dir=<directory-to-exclude> --include=\*<Files to include> "<Line to be replaced>" ./ | sed -i <extension> 's/.*<Line to be replaced>.*/<New line to be added>/'
The question asks for solutions using sed, but if that's not a hard requirement then there is another option which might be a wiser choice.
The accepted answer suggests sed -i and describes it as replacing the file in-place, but -i doesn't really do that and instead does the equivalent of sed pattern file > tmp; mv tmp file, preserving ownership and modes. This is not ideal in many circumstances. In general I do not recommend running sed -i non-interactively as part of an automatic process--it's like setting a bomb with a fuse of an unknown length. Sooner or later it will blow up on someone.
To actually edit a file "in place" and replace a line matching a pattern with some other content you would be well served to use an actual text editor. This is how it's done with ed, the standard text editor.
printf '%s\n' '/TEXT_TO_BE_REPLACED/' d i 'This line is removed by the admin' . w q | \
ed -s /tmp/foo > /dev/null
Note that this only replaces the first matching line, which is what the question implied was wanted. This is a material difference from most of the other answers.
That disadvantage aside, there are some advantages to using ed over sed:
You can replace the match with one or multiple lines without any extra effort.
The replacement text can be arbitrarily complex without needing any escaping to protect it.
Most importantly, the original file is opened, modified, and saved. A copy is not made.
How it works
How it works:
printf will use its first argument as a format string and print each of its other arguments using that format, effectively meaning that each argument to printf becomes a line of output, which is all sent to ed on stdin.
The first line is a regex pattern match which causes ed to move its notion of "the current line" forward to the first line that matches (if there is no match the current line is set to the last line of the file).
The next is the d command which instructs ed to delete the entire current line.
After that is the i command which puts ed into insert mode;
after that all subsequent lines entered are written to the current line (or additional lines if there are any embedded newlines). This means you can expand a variable (e.g. "$foo") containing multiple lines here and it will insert all of them.
Insert mode ends when ed sees a line consisting of .
The w command writes the content of the file to disk, and
the q command quits.
The ed command is given the -s switch, putting it into silent mode so it doesn't echo any information as it runs,
the file to be edited is given as an argument to ed,
and, finally, stdout is thrown away to prevent the line matching the regex from being printed.
Some Unix-like systems may (inappropriately) ship without an ed installed, but may still ship with an ex; if so you can simply use it instead. If have vim but no ex or ed you can use vim -e instead. If you have only standard vi but no ex or ed, complain to your sysadmin.
It is as similar to above one..
sed 's/[A-Za-z0-9]*TEXT_TO_BE_REPLACED.[A-Za-z0-9]*/This line is removed by the admin./'
Below command is working for me. Which is working with variables
sed -i "/\<$E\>/c $D" "$B"
I very often use regex to extract data from files I just used that to replace the literal quote \" with // nothing :-)
cat file.csv | egrep '^\"([0-9]{1,3}\.[0-9]{1,3}\.)' | sed s/\"//g | cut -d, -f1 > list.txt
I know how to do a search and replace amongst group of files:
perl -pi -w -e 's/search/replace/g;' *.php
So I can use that to search for a keyword or phrase and change it. But I have a more complicated task I dont know how to do.
I want to do a search and replace among all my php files to search for a specific Keyword and replace it with the File Name minus the extension.
Example: Search the file Mountains.php for the keyword Trees and everywhere you see Trees, replace it with Mountains
Of course I want to be able to do that in batch, for a few hundred php files all with different names, however, all containing the search term Trees.
If someone is looking for an extra challenge, haha, it would be even better if I could do a more complex scenario such as....
Example: Search the file MountainTowns.php for the keyword Trees and everywhere you see Trees, replace it with "Mountain Towns" (note the extra space, Capital Letters could would indicate where spaces go)
Thanks for your time and considering my question.
Well, the filename is in $ARGV, so there is not much more work needed.
perl -i -pe '($x=$ARGV)=~s{.php$}{};s{Trees}{$x}g' BlueMountains.php RedMountains.php
Add in
$x=~s{(.)([A-Z])}{$1 $2}g;
to add the space before upcased letters, for a complete line of
perl -i -pe '($x=$ARGV)=~s{.php$}{};$x=~s{(.)([A-Z])}{$1 $2}g;s{Trees}{$x}g' BlueRedMountains.php
This might work for you:
printf "%s\n" *.php |perl -pwe 's|(.*).php|perl -pi -we "s/Trees/$1/g;" $&|' | bash
This uses perl to write a script to do you bidding.
Other little languages could be employed, like awk or:
printf "%s\n" *.php |sed 'h;s/\.php//;s/\B[A-Z]/ &/;G;s|\(.*\)\n\(.*\)|sed -i "s/Trees/\1/g" \2|' | bash
This uses sed to provide a solution for the second request.
You want a separate replacement for each file, so run a separate search and replace for each:
for file in *.php; do sed -i "s/foo/${file%.*}/g" "$file"; done
And your second request is a bit harder, it at least requires a subshell.
for file in *; do sed -i "s/bar/$(echo ${file%.*} | sed 's/\(.\)\([A-Z]\)/\1 \2/')/g" "$file"; done
It's a bit more readable if you put it in a script:
#!/bin/bash
for file in "$#"; do
replacement=$(echo ${file%.*} | sed 's/\(.\)\([A-Z]\)/\1 \2/')
sed -i "s/bar/$replacement/g" "$file";
done
This will work over all the arguments passed it, so call with ./script.sh *.php.
I have a set of 10 CSV files, which normally have a an entry of this kind
a,b,c,d
d,e,f,g
Now due to some error entries in this file have become of this kind
a,b,c,d
d,e,f,g
,,,
h,i,j,k
Now I want to remove the line with only commas in all the files. These files are on a Linux filesystem.
Any command that you recommend that can replaces the erroneous lines in all the files.
It depends on what you mean by replace. If you mean 'remove', then a trivial variant on #wnoise's solution is:
grep -v '^,,,$' old-file.csv > new-file.csv
Note that this deletes just those lines with exactly three commas. If you want to delete mal-formed lines with any number of commas (including zero) - and no other characters on the line, then:
grep -v '^,*$' ...
There are endless other variations on the regex that would deal with other scenarios. Dealing with full CSV data with commas inside quotes starts to need something other than a regex machine. It can be done, within broad limits, especially in more complex regex systems such as PCRE or Perl. But it requires more work.
Check out Mastering Regular Expressions.
sed 's/,,,/replacement/' < old-file.csv > new-file.csv
optionally followed by
mv new-file.csv old-file.csv
Replace or remove, your post is not clear... For replacement see wnoise's answer. For removing, you could use
awk '$0 !~ /,,,/ {print}' <old-file.csv > new-file.csv
What about trying to keep only lines which are matching the desired format instead of handling one exception ?
If the provided input is what you really want to match:
grep -E '[a-z],[a-z],[a-z],[a-z]' < oldfile.csv > newfile.csv
If the input is different, provide it, the regular expression should not be too hard to write.
Do you want to replace them with something, or delete them entirely? Either way, it can be done with sed. To delete:
sed -i -e '/^,\+$/ D' yourfile1.csv yourfile2.csv ...
To replace: well, see wnoise's answer, or if you don't want to create new files with the output,
sed -i -e '/^,\+$/ s//replacement/' yourfile1.csv yourfile2.csv ...
or
sed -i -e '/^,\+$/ c\
replacement' yourfile1.csv yourfile2.csv ...
(that should be entered exactly as is, including the line break). Of course, you can also do this with awk or perl or, if you're only deleting lines, even grep:
egrep -v '^,+$' < oldfile.csv > newfile.csv
I tested these to make sure they work, but I'd advise you to do the same before using them (just in case). You can omit the -i option from sed, in which case it'll print out the results (rather than writing them back to the file), or omit the output redirection >newfile.csv from grep.
EDIT: It was pointed out in a comment that some features of these sed commands only work on GNU sed. As far as I can tell, these are the -i option (which can be replaced with shell redirection, sed ... <infile >outfile ) and the \+ modifier (which can be replaced with \{1,\} ).
Most simply:
$ grep -v ,,,, oldfile > newfile
$ mv newfile oldfile
yes, awk or grep are very good option if you are working in linux platform. However you can use perl regex for other platform. using join & split options.