# Read and edit multiple files using a while loop **URL:** \ **Category:** Shell Programming and Scripting\ **Created:** [August 27, 2010, 5:19am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297 "2010-08-27T05:19:02Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![cyberfrog](https://community.unix.com/letter_avatar/cyberfrog/32/6_22734026db12803ebb3e059622ac3534.png) [@cyberfrog](https://community.unix.com/u/cyberfrog)\ **Post date:** [August 27, 2010, 5:19am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297/1 "2010-08-27T05:19:02Z")
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: ```nohighlight :1,$s/search_str/replace_str/g ``` but I am not sure how to automate the \ of these vis commands when I am putting this in a while loop. i.e. if a loop the first time I cannot actually initiate the above command without pressing the return button, is there a special command for this? Thanks ---
**Author:** ![zaxxon](https://community.unix.com/user_avatar/community.unix.com/zaxxon/32/660_2.png) [@zaxxon](https://community.unix.com/u/zaxxon)\ **Post date:** [August 27, 2010, 5:34am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297/2 "2010-08-27T05:34:05Z")
The syntax you use can be also used in sed. If your sed has the -i option (perl has an option like this too), you can just edit the files directly. Else you might want to write the output of sed to a tmp file and mv it back to the original file. If you can print the files with a find and hand them over to sed -i with -exec or xargs for example. If you feed the filenames from a file, then a while loop may be a good idea. ---
**Author:** ![cyberfrog](https://community.unix.com/letter_avatar/cyberfrog/32/6_22734026db12803ebb3e059622ac3534.png) [@cyberfrog](https://community.unix.com/u/cyberfrog)\ **Post date:** [August 27, 2010, 6:08am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297/3 "2010-08-27T06:08:41Z")
Sorry not too familiar with SED commands so breaking this down so I have tried this comamnd: ```nohighlight sed -e '1,$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? ---
**Author:** ![felipe.vinturin](https://community.unix.com/user_avatar/community.unix.com/felipe.vinturin/32/1840_2.png) [@felipe.vinturin](https://community.unix.com/u/felipe.vinturin)\ **Post date:** [August 27, 2010, 6:23am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297/4 "2010-08-27T06:23:14Z")
Ok! We have two options: 1. As zaxxon commented, if your sed supports the "-i" option, in place change, use it. ```nohighlight sed -i -e '1,$s/old string/new string/g' myfirstfileinloop.txt ``` 1. If it does not, you must redirect the output, like the following: ```nohighlight ls -1 | while read fname do myFileTmp=${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 "${fname}" done ``` ---
**Author:** ![felipe.vinturin](https://community.unix.com/user_avatar/community.unix.com/felipe.vinturin/32/1840_2.png) [@felipe.vinturin](https://community.unix.com/u/felipe.vinturin)\ **Post date:** [August 27, 2010, 6:26am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297/5 "2010-08-27T06:26:50Z")
The second option will change all files in a directory, you want one file, just: ```nohighlight sed -e '1,$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: ```nohighlight 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 ``` ---
**Author:** ![cyberfrog](https://community.unix.com/letter_avatar/cyberfrog/32/6_22734026db12803ebb3e059622ac3534.png) [@cyberfrog](https://community.unix.com/u/cyberfrog)\ **Post date:** [August 27, 2010, 6:26am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297/6 "2010-08-27T06:26:50Z")
It supports sed but it seems to throw this illegal message: ```nohighlight sed: illegal option -- i Usage: sed [-n] [-e script] [-f source_file] [file...] ``` ---
**Author:** ![felipe.vinturin](https://community.unix.com/user_avatar/community.unix.com/felipe.vinturin/32/1840_2.png) [@felipe.vinturin](https://community.unix.com/u/felipe.vinturin)\ **Post date:** [August 27, 2010, 6:28am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297/7 "2010-08-27T06:28:54Z")
It is because sed does not support the: "-i" option. Try the second option. Also, in what platform are you executing it? Regards. ---
**Author:** ![cyberfrog](https://community.unix.com/letter_avatar/cyberfrog/32/6_22734026db12803ebb3e059622ac3534.png) [@cyberfrog](https://community.unix.com/u/cyberfrog)\ **Post date:** [August 27, 2010, 7:04am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297/8 "2010-08-27T07:04:34Z")
will try, the platform is HP-UX ---------- Post updated at 03:04 AM ---------- Previous update was at 02:36 AM ---------- Its the HP Unix platform Regards ---
**Author:** ![felipe.vinturin](https://community.unix.com/user_avatar/community.unix.com/felipe.vinturin/32/1840_2.png) [@felipe.vinturin](https://community.unix.com/u/felipe.vinturin)\ **Post date:** [August 27, 2010, 8:01am UTC](https://community.unix.com/t/read-and-edit-multiple-files-using-a-while-loop/272297/9 "2010-08-27T08:01:42Z")
Were you able to test it?