I'm trying to change a variable in a .txt file but I can't figure how. I've looked on internet and tried what was written but it doesn't work. I get the following error message :
sed: 1: "abc.txt": command a expects \ followed by text
Here was what I originally tried to run:
sed -i 's/Hi/Good Morning/' abc.txt
Check your man page for sed. -i probably requires a suffix argument.
-i extension
Edit files in-place, saving backups with the specified extension. If a zero-length extension is given,
no backup will be saved. It is not recommended to give a zero-length extension when in-place editing
files, as you risk corruption or partial content in situations where disk space is exhausted, etc.
What's happening is that sed is taking 's/Hi/Good Morning/' to be the argument to -i, and then considering abc.txt to be the sed command itself.
By adding a proper backup extension to the command, it will work like so:
$ cat abc.txt
Hi, How are you
$ sed -i .bak 's/Hi/Good Morning/' abc.txt
$ cat abc.txt
Good Morning, How are you
$ cat abc.txt.bak
Hi, How are you
Related
I would like to run a find and replace on an HTML file through the command line.
My command looks something like this:
sed -e s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html > index.html
When I run this and look at the file afterward, it is empty. It deleted the contents of my file.
When I run this after restoring the file again:
sed -e s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html
The stdout is the contents of the file, and the find and replace has been executed.
Why is this happening?
When the shell sees > index.html in the command line it opens the file index.html for writing, wiping off all its previous contents.
To fix this you need to pass the -i option to sed to make the changes inline and create a backup of the original file before it does the changes in-place:
sed -i.bak s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html
Without the .bak the command will fail on some platforms, such as Mac OSX.
An alternative, useful, pattern is:
sed -e 'script script' index.html > index.html.tmp && mv index.html.tmp index.html
That has much the same effect, without using the -i option, and additionally means that, if the sed script fails for some reason, the input file isn't clobbered. Further, if the edit is successful, there's no backup file left lying around. This sort of idiom can be useful in Makefiles.
Quite a lot of seds have the -i option, but not all of them; the posix sed is one which doesn't. If you're aiming for portability, therefore, it's best avoided.
sed -i 's/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g' index.html
This does a global in-place substitution on the file index.html. Quoting the string prevents problems with whitespace in the query and replacement.
use sed's -i option, e.g.
sed -i bak -e s/STRING_TO_REPLACE/REPLACE_WITH/g index.html
To change multiple files (and saving a backup of each as *.bak):
perl -p -i -e "s/\|/x/g" *
will take all files in directory and replace | with x
this is called a “Perl pie” (easy as a pie)
You should try using the option -i for in-place editing.
Warning: this is a dangerous method! It abuses the i/o buffers in linux and with specific options of buffering it manages to work on small files. It is an interesting curiosity. But don't use it for a real situation!
Besides the -i option of sed
you can use the tee utility.
From man:
tee - read from standard input and write to standard output and files
So, the solution would be:
sed s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html | tee | tee index.html
-- here the tee is repeated to make sure that the pipeline is buffered. Then all commands in the pipeline are blocked until they get some input to work on. Each command in the pipeline starts when the upstream commands have written 1 buffer of bytes (the size is defined somewhere) to the input of the command. So the last command tee index.html, which opens the file for writing and therefore empties it, runs after the upstream pipeline has finished and the output is in the buffer within the pipeline.
Most likely the following won't work:
sed s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html | tee index.html
-- it will run both commands of the pipeline at the same time without any blocking. (Without blocking the pipeline should pass the bytes line by line instead of buffer by buffer. Same as when you run cat | sed s/bar/GGG/. Without blocking it's more interactive and usually pipelines of just 2 commands run without buffering and blocking. Longer pipelines are buffered.) The tee index.html will open the file for writing and it will be emptied. However, if you turn the buffering always on, the second version will work too.
sed -i.bak "s#https.*\.com#$pub_url#g" MyHTMLFile.html
If you have a link to be added, try this. Search for the URL as above (starting with https and ending with.com here) and replace it with a URL string. I have used a variable $pub_url here. s here means search and g means global replacement.
It works !
The problem with the command
sed 'code' file > file
is that file is truncated by the shell before sed actually gets to process it. As a result, you get an empty file.
The sed way to do this is to use -i to edit in place, as other answers suggested. However, this is not always what you want. -i will create a temporary file that will then be used to replace the original file. This is problematic if your original file was a link (the link will be replaced by a regular file). If you need to preserve links, you can use a temporary variable to store the output of sed before writing it back to the file, like this:
tmp=$(sed 'code' file); echo -n "$tmp" > file
Better yet, use printf instead of echo since echo is likely to process \\ as \ in some shells (e.g. dash):
tmp=$(sed 'code' file); printf "%s" "$tmp" > file
And the ed answer:
printf "%s\n" '1,$s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g' w q | ed index.html
To reiterate what codaddict answered, the shell handles the redirection first, wiping out the "input.html" file, and then the shell invokes the "sed" command passing it a now empty file.
I was searching for the option where I can define the line range and found the answer. For example I want to change host1 to host2 from line 36-57.
sed '36,57 s/host1/host2/g' myfile.txt > myfile1.txt
You can use gi option as well to ignore the character case.
sed '30,40 s/version/story/gi' myfile.txt > myfile1.txt
With all due respect to the above correct answers, it's always a good idea to "dry run" scripts like that, so that you don't corrupt your file and have to start again from scratch.
Just get your script to spill the output to the command line instead of writing it to the file, for example, like that:
sed -e s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html
OR
less index.html | sed -e s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g
This way you can see and check the output of the command without getting your file truncated.
Imagine the following data stored in file data.txt
1, StringString, AnotherString 545
I want to replace "StringString" with "Strung" with the following code
sed -ir 's/String+/Strung/g' data.txt
But it won't work. This works though:
sed -ri 's/String+/Strung/g' data.txt
I don't see any reason why the order of option flags would matter. Is it a bug or is there an explanation?
Please note that I'm not looking for a workaround but rather why the order of -ir and -ri matters.
Sidenotes: The switch -i "edits the file in place" while -r allows "extended regular expression" (allowing the + operator). I'm running sed 4.2.1 Dec. 2010 on Ubuntu 12.10.
When doing -ir you are specifying that "r" should be the suffix for the backup file.
You should be able to do -i -r if you need them in that order
Did you check sed --help or man sed?
-i[SUFFIX], --in-place[=SUFFIX]
edit files in place (makes backup if extension supplied).
The default operation mode is to break symbolic and hard links.
This can be changed with --follow-symlinks and --copy.
I am on macOS High Sierra, and I've had a few issues with sed,
after spending a day on Google and this site, I've honestly tried everything I could think of and was suggested.
I have an example.txt file with 3 lines.
line1
line2
line3
The 3 lines can be anything, I do not know them upfront. (scenario)
And at some point I do know what the line is going to be.
All I wish to achieve is to use 'whatever' onliner that basically says:
in that file, replace line 2, with the new data.
sed -i "2s/.*/$NEW_DATA/" "$FILENAME"
This should work, but on macOS, this does not.
sed -ie "2s/.*/$NEW_DATA/" "$FILENAME"
Note the e? Someone on here suggested to add an e, and yes, that works.. but it means it adds the e behind the .txt. I end up with 2 files, example.txt and example.txte
sed -i'' "2s/.*/$NEW_DATA/" "$FILENAME"
Note the '' behind -i, and yes, without a space? This should work too.
It doesn't, it will complain that command c requires \
I could go on, but the request is quite simple:
on macOS, in a bash shell script, how do I simply replace a specified line of text in a .txt file, with a completely new line of text -- not knowing what the line of text was before?
If this can be a simple macOS one liner with awk or whatever, that's fine. It doesn't have to be sed. But when I search this site, it seems to be the recommended one to go with in this regards.
From the sed man page in macOS:
-i extension
Edit files in-place, saving backups with the specified extension.
If a zero-length extension is given, no backup will be saved.
Therefore this can be used to replace line 2 without keeping backup:
sed -i '' "2s/.*/$NEW_DATA/" testfile.txt
If the goal is just to replace contents of line 2 awk could also be used, for example:
awk 'NR==2{$0="your content"}1' testfile.txt > testfile.tmp && mv testfile.tmp testfile.txt
I want to find specific text in a directory, and then delete the lines from the files that include the specific text.
Now I have two questions:
How can I achieve the task?
What is wrong with What I have tried? I have tried the methods below, but failed. the details are following:
grep -rnw "./" -e "webdesign"
This searches the current directory with pattern "webdesign", and I get the result:
.//pages/index.html:1:{% load webdesign %}
.//pages/pricing.html:1:{% load webdesign %}
.//prototypes.py:16: 'django.contrib.webdesign',
Then I use sed to remove the lines from those files, which doesn't work, only get blank file ( I mean it deletes all my file content):
sed -i "/webdesign/d" ./pages/index.html
or
sed "/webdesign/d" ./pages/index.html > ./pages/index.html
My software environment is: OS X Yosemite, Mac Terminal, Bash
A loop in bash will do the trick provided that there are no filenames with spaces (in which case other solutions are possible, but this is the simplest)
for i in `grep -lrnw "yourdirectory/" -e "webdesign"`
do
sed "/webdesign/d" $i > $i.tmp
# safety to avoid destroying the file if problem arises (disk full?)
if [ $? = 0 ] ; then
mv -f $i.tmp $i
fi
done
note that you should not locate this script in the current directory because it contains webdesign and it will be modified as well :)
Thanks to choroba, I know that -i option doesn't work like wished. But it has another meaning or it would be rejected by the opt parser. It has something to do with suffixes, well, it doesn't matter now, but it's difficult to see the problem at first.
Without -i you cannot work on a file in-place. And redirecting output to the input just destroys the input file (!). That's why your solution did not work.
You can install GNU sed that supports the -i option, then
sed -i '/webdesign/d' files
should work. Note that it's safer to use -i~ to create a backup.
You cannot write to the same file you're reading from, that's why
sed /webdesign/d file > file
doesn't work (it overwrites the file before you can read anything from it). Create a temporary file
sed /webdesign/d file > file.tmp
mv file.tmp file
On my Mac, when I try to run:
sed -i 2d file.csv
from the answer to Unix script to remove the first line of a CSV file, I get the following error:
sed: 1: "file.csv": invalid command code f
What can I do if I would like to delete the first two lines of file.csv?
On a Mac, the BSD sed requires the suffix for the backup (but the suffix can be an empty string, '') — it is not optional as it is with GNU sed. Hence, your command is being interpreted as "backup the file with the suffix 2d and … oops, the script you gave is file.csv, but f isn't a sed command".
sed -i .bak -e 2d file.csv
This deletes the first line of data from the CSV file (leaving the heading line in place).
If you want to write the code so it works with both BSD and GNU sed, then you have to attach the suffix to the -i option (GNU sed requires the suffix attached to the -i option; that's how it identifies whether there's an optional suffix or not):
sed -i.bak -e 2d file.csv
Note that you can't use an empty suffix and have the command work with both BSD sed and GNU sed.
The -e isn't necessary in either command line, but I quite often use it. I also often quote the command in single quotes, though it isn't necessary here.
If you want to delete the first two data lines, use 2,3d as the command. If you want to delete the first two lines, use 1,2d.
If you don't want the backup, then you can either remove it after the sed command completes (easiest) or use the two stage or three stage dance:
sed 2d file.csv > file.csv.bak &&
mv file.csv.bak file.csv # Oops; there went the links
sed 2d file.csv > file.csv.bak &&
cp file.csv.bak file.csv
rm -f file.csv.bak
With these, you might need to add trap commands to clean up the intermediate .bak file if an interrupt or other signal terminates the script.
To quote from the Apple documentation for sed — which was originally quoted by Diego in an answer which he chose to delete, the -i option takes an argument which indicates the extension to use for backup copies.
-i extension
Edit files in-place, saving backups with the specified extension. If a zero-length extension is given, no backup will be saved. It is not recommended to give a zero-length extension when in-place editing files, as you risk corruption or partial content in situations where disk space is exhausted, etc.
sed -i.bak '2,3d' filename.csv will delete lines 1 and 2 (assuming you have headers)
What this command does is edits the file being referenced while simultaneously creating a backup of the original file (hence the usage of .bak). The line deletion '2,3d' will delete the 2nd and 3rd line of the original file.