CODEWITHSUNDEEP
sedsubstitution
Asaf
Asaf

Reputation: 93

Single sed command for multiple substitutions?

I use sed to substitute text in files. I want to give sed a file which contains all the strings to be searched and replaced in a given file.

It goes over .h and .cpp files. In each file it searches for file names which are included in it. If found, it substitutes for example "a.h" with "<a.h>" (without the quotes).

The script is this:

For /F %%y in (all.txt) do 
   for /F %%x in (allFilesWithH.txt) do
       sed -i s/\"%%x\"/"\<"%%x"\>"/ %%y

I don't want to run sed several times (as the number of files names in input.txt.) but I want to run a single sed command and pass it input.txt as input.

How can I do it?

P.S I run sed from VxWorks Development shell, so it doesn't have all the commands that the Linux version does.

Upvotes: 5

Views: 14362

Answers (3)

Peter Mortensen
Peter Mortensen

Reputation: 31599

You can eliminate one of the loops so sed only needs to be called once per file. Use the -f option to specify more than one substitution:

For /F %%y in (all.txt) do 
    sed -i -f allFilesWithHAsSedScript.sed %%y

allFilesWithHAsSedScript.sed derives from allFilesWithH.txt and would contain:

s/\"file1\"/"\<"file1"\>"/
s/\"file2\"/"\<"file2"\>"/
s/\"file3\"/"\<"file3"\>"/
s/\"file4\"/"\<"file4"\>"/

(In the article Common threads: Sed by example, Part 3 there are many examples of sed scripts with explanations.)

Don't get confuSed (pun intended).

Upvotes: 8

reinierpost
reinierpost

Reputation: 8591

What I'd do is change allFilesWithH.txt into a sed command using sed.

(When forced to use sed. I'd actually use Perl instead, it can also do the search for *.h files.)

Upvotes: 0

Cascabel
Cascabel

Reputation: 496802

sed itself has no capability to read filenames from a file. I'm not familiar with the VxWorks shell, and I imagine this is something to do with the lack of answers... So here are some things that would work in bash - maybe VxWorks will support one of these things.

sed -i 's/.../...' `cat all.txt`

sed -i 's/.../...' $(cat all.txt)

cat all.txt | xargs sed -i 's/.../...'

And really, it's no big deal to invoke sed several times if it gets the job done:

cat all.txt | while read file; do sed -i 's/.../.../' $file; done

for file in $(cat all.txt); do   # or `cat all.txt`
    sed -i 's/.../.../' $file
done

Upvotes: 4

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