I want to modify file content with shell script like replace the line 3 in file with a new string, and then save to the original file. Can anyone give advice to achieve that?
It's a bit unusual to do that with vim from a shell script, but since you asked:
vim -es '+3s/.*/a new string' '+wq' file
Usually, you would chose another tool like (sed -i is in-place edit):
sed -i '3s/.*/a new string/' file
Or with awk
gawk -i inplace 'NR==3{$0="a new string"}1' file
In a Unix-like system, you can use sed to replace the content of specific line. For example, below command will replace the 3rd line with "HelloWorld" in text.txt file.
sed -i '3c HelloWorld' text.txt
In case you only want to change part of 3rd line content, you can use :
sed -i '3s/aaa/bbb/' text.txt
this will only replace string "aaa" into "bbb" in 3rd line.
ed would be more appropriate than sed or vim, as it is designed to edit files in-place programmatically. (sed is the stream version of ed; -i is a non-standard extension.)
printf '3s/.*/new stuff/\nw\n' | ed my_file.txt
Related
Is it possible with the use of some linux tool change lines in file like following:
was:
status:<whatever>
become:
status:"red"
UPDATE
The best solution:
awk 'BEGIN{FS=OFS=":"} $1 ~ /status/ {$2="\"red\""}1' file
This will print output and we can redirect it to file or whatever.
sed is the Stream EDitor, its purpose is to edit text streams, not text files. It really is the wrong tool for the job here. You should use a text file editor such as ed instead:
ed -- /path/to/file <<-HERE
,s/^status:.*/status:"red"
w
q
HERE
With GNU sed:
sed -E 's/^(status:).*/\1"red"/' file
With a string:
s="red"
sed -E 's/^(status:).*/\1"'"${s//\//}"'"/' file
If you want to edit your file "in place" use sed's option -i.
If your Input_file is same as shown sample then following may help you in same.
echo "status:<whatever>" | sed 's/\(.*:\)\(.*\)/\1"red"/g'
I am looking to perform an operation with sed that appends to a specific part of a series of files like to:
sed -i "s/test:\n/&$(<test.file)/g" foo.txt
Is there a way I can take the output of a file or some BASH varaible and place it into sed for input into a file.
sed '/^test:$/{r test.file
d}' foo.txt
Should do the trick. Note that the literal newline after the filename is not necessary in all versions of sed, but is advisable. The r command reads the contents of the named file.
Suppose my file a.conf is as following
Include /1
Include /2
Include /3
I want to replace "Include /2" with a new line, I write the code in .sh file :
line="Include /2"
rep=""
sed -e "s/${line}/${rep}/g" /root/new_scripts/a.conf
But after running the sh file, It give me the following error
sed: -e expression #1, char 14: unknown option to `s'
If you are using a newer version of sed you can use -i to read from and write to the same file. Using -i you can specify a file extension so a backup will be made, incase something went wrong. Also you don't need to use the -e flag unless you are using multiple commands
sed -i.bak "s/${line}/${rep}/g" /root/new_scripts/a.conf
I have just noticed that as the variables you are using are quoted strings you may want to use single quotes around your sed expression. Also your string contains a forward slash, to avoid any errors you can use a different delimiter in your sed command (the delimiter doesn't need to be a slash):
sed -i.bak 's|${line}|${rep}|g' /root/new_scripts/a.conf
You have to write the changes to a new file and then, move the new file over the old one. Like this:
line="Include 2"
rep=""
sed -e "s/${line}/${rep}/g" /root/new_scripts/a.conf > /root/new_scripts/a.conf-new
mv /root/new_scripts/a.conf-new /root/new_scripts/a.conf
The redirection (> /root/new_scripts/a.conf) wipes the contents of the file before sed can see it.
You need to pass the -i option to sed to edit the file in-place:
sed -i "s/${line}/${rep}/g" /root/new_scripts/a.conf
You can also ask sed to create a backup of the original file:
sed -i.bak "s/${line}/${rep}/g" /root/new_scripts/a.conf
So, if you have to replace a substring in a file, you can use sed command like this, say we have a file as file.txt, so replacing a substring in it can be done like this
searchString="abc";
replaceString="def";
sed -i '' "s|$searchString|$replaceString|g" file.txt
This will all the occurrences of "abc" with "def" in file.txt. Also, this keeps a check for any / character present in the variables used, and with no backup file made.
I'd like edit a file with sed on OS X. I'm using the following command:
sed 's/oldword/newword/' file.txt
The output is sent to the terminal. file.txt is not modified. The changes are saved to file2.txt with this command:
sed 's/oldword/newword/' file1.txt > file2.txt
However I don't want another file. I just want to edit file1.txt. How can I do this?
I've tried the -i flag. This results in the following error:
sed: 1: "file1.txt": invalid command code f
You can use the -i flag correctly by providing it with a suffix to add to the backed-up file. Extending your example:
sed -i.bu 's/oldword/newword/' file1.txt
Will give you two files: one with the name file1.txt that contains the substitution, and one with the name file1.txt.bu that has the original content.
Mildly dangerous
If you want to destructively overwrite the original file, use something like:
sed -i '' 's/oldword/newword/' file1.txt
^ note the space
Because of the way the line gets parsed, a space is required between the option flag and its argument because the argument is zero-length.
Other than possibly trashing your original, I’m not aware of any further dangers of tricking sed this way. It should be noted, however, that if this invocation of sed is part of a script, The Unix Way™ would (IMHO) be to use sed non-destructively, test that it exited cleanly, and only then remove the extraneous file.
I've similar problem with MacOS
sed -i '' 's/oldword/newword/' file1.txt
doesn't works, but
sed -i"any_symbol" 's/oldword/newword/' file1.txt
works well.
The -i flag probably doesn't work for you, because you followed an example for GNU sed while macOS uses BSD sed and they have a slightly different syntax.
All the other answers tell you how to correct the syntax to work with BSD sed. The alternative is to install GNU sed on your macOS with:
brew install gsed
and then use it instead of the sed version shipped with macOS (note the g prefix), e.g:
gsed -i 's/oldword/newword/' file1.txt
If you want GNU sed commands to be always portable to your macOS, you could prepend "gnubin" directory to your path, by adding something like this to your .bashrc/.zshrc file (run brew info gsed to see what exactly you need to do):
export PATH="/usr/local/opt/gnu-sed/libexec/gnubin:$PATH"
and from then on the GNU sed becomes your default sed and you can simply run:
sed -i 's/oldword/newword/' file1.txt
sed -i -- "s/https/http/g" file.txt
You can use -i'' (--in-place) for sed as already suggested. See: The -i in-place argument, however note that -i option is non-standard FreeBSD extensions and may not be available on other operating systems. Secondly sed is a Stream EDitor, not a file editor.
Alternative way is to use built-in substitution in Vim Ex mode, like:
$ ex +%s/foo/bar/g -scwq file.txt
and for multiple-files:
$ ex +'bufdo!%s/foo/bar/g' -scxa *.*
To edit all files recursively you can use **/*.* if shell supports that (enable by shopt -s globstar).
Another way is to use gawk and its new "inplace" extension such as:
$ gawk -i inplace '{ gsub(/foo/, "bar") }; { print }' file1
This creates backup files. E.g. sed -i -e 's/hello/hello world/' testfile for me, creates a backup file, testfile-e, in the same dir.
You can use:
sed -i -e 's/<string-to-find>/<string-to-replace>/' <your-file-path>
Example:
sed -i -e 's/Hello/Bye/' file.txt
This works flawless in Mac.
If you need to substitute more than one different words:
sed -i '' -e 's/_tools/tools/' -e 's/_static/static/' test.txt
sed 's/$/<br>/' mytext.txt
worked but output it all on the command line. I want it to just do the replacement WITHIN the specified file itself. Should I be using another tool?
If you have gnu sed, you can use the -i option, which will do the replacement in place.
sed -i 's/$/<br>/' mytext.txt
Otherwise you will have to redirect to another file and rename it over the old one.
sed 's/$/<br>/' mytext.txt > mytext.txt.new && mv mytext.txt.new mytext.txt
Just for completeness. On Mac OS X (which uses FreeBSD sed) you have to use an additional null-string "" for in-place file editing without backup:
sed -i "" 's/$/<br>/' mytext.txt
As an alternative to using sed for no-backup in-place file editing, you may use ed(1), which, however, reads the entire file into memory before operating on it.
printf '%s\n' H 'g/$/s//<br>/g' ',p' | ed -s test.file # print to stdout
printf '%s\n' H 'g/$/s//<br>/g' wq | ed -s test.file # in-place file edit
For more information on ed(1) see:
"Editing files with the ed text editor from scripts",
http://wiki.bash-hackers.org/doku.php?id=howto:edit-ed
If you have an up-to-date sed, just use sed -i or sed --in-place, which will modify the actual file itself.
If you want a backup, you need to supply a suffix for it. So sed -i.bak or sed --in-place=.bak will create a backup file with the .bak suffix.
Use this! Seriously! You'll appreciate it a lot the first time you damage your file due to a mistyped sed command or wrong assumption about the data in the file.
Use the redirection symbol i.e.
sed 's/$/<br>/' mytext.txt > mytext2.txt && mv mytext2.txt mytext.txt