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Read and edit multiple files using a while loop

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# 1  
Old 08-27-2010
Read and edit multiple files using a while loop
Hi all,
I would like to simply read a file which lists a number of pathnames and files, then search and replace key strings using a few vi commands:

Code:
:1,$s/search_str/replace_str/g<return>


but I am not sure how to automate the <return> of these vis commands when I am putting this in a while loop.

i.e. if a loop the first time I cannot actually initiate the above command without pressing the return button, is there a special command for this?

Thanks
Last edited by Scott; 08-27-2010 at 07:29 AM.. Reason: Code tags
# 2  
Old 08-27-2010
The syntax you use can be also used in sed. If your sed has the -i option (perl has an option like this too), you can just edit the files directly. Else you might want to write the output of sed to a tmp file and mv it back to the original file.
If you can print the files with a find and hand them over to sed -i with -exec or xargs for example.
If you feed the filenames from a file, then a while loop may be a good idea.
# 3  
Old 08-27-2010
Sorry not too familiar with SED commands so breaking this down so I have tried this comamnd:

Code:
sed -e '1,$s/old string/new string/g' myfirstfileinloop.txt

now when I execute this it prints to the terminal including the new strings that were replaced yet when I open the actual file it still remains the old same and nothing has changed?
Last edited by Scott; 08-27-2010 at 07:29 AM.. Reason: Code tags
# 4  
Old 08-27-2010
Ok!

We have two options:

1. As zaxxon commented, if your sed supports the "-i" option, in place change, use it.
Code:
sed -i -e '1,$s/old string/new string/g' myfirstfileinloop.txt

2. If it does not, you must redirect the output, like the following:
Code:
ls -1 | while read fname
do
      myFileTmp=${fname}.tmp
      sed -e '1,$s/old string/new string/g' "${fname}" > "${myFileTmp}"
      # If you want to remove the original file uncomment the line below
      [ $? -eq 0 ] && rm -f "${fname}"
done

# 5  
Old 08-27-2010
The second option will change all files in a directory, you want one file, just:
Code:
sed -e '1,$s/old string/new string/g' myfirstfileinloop.txt > myfirstfileinloop.txt.new

Also, in the second option you can rename the tmp file to the original one:
Code:
ls -1 | while read fname
do
      myFileTmp=${fname}.tmp
      sed -e '1,$s/old string/new string/g' "${fname}" > "${myFileTmp}"
      # If you want to change back to the original file uncomment the line below
      # [ $? -eq 0 ] && mv "${myFileTmp}" "${fname}"
done

# 6  
Old 08-27-2010
It supports sed but it seems to throw this illegal message:

Code:
sed: illegal option -- i
Usage: sed [-n] [-e script] [-f source_file] [file...]

Last edited by Scott; 08-27-2010 at 07:32 AM.. Reason: Code tags, please...
# 7  
Old 08-27-2010
It is because sed does not support the: "-i" option. Try the second option.

Also, in what platform are you executing it?

Regards.
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