Több file tartalmának csoportos szerkesztése

RTFM, sed -i: edit files in place

Pl csere:
sed -ie 's/ezt/erre/' file1 file2 ...

SED FAQ, 4.4 : How do I make substitutions in every file in a directory, or in a complete directory tree?

4.4.1. - Perl solution

(Yes, we know this is a FAQ file for sed, not perl, but the
solution is so simple that it has to be noted. Also, perl and
sed share a very similar syntax here.)

perl -pi.bak -e 's|foo|bar|g' filelist

For each file in the filelist, perl renames the source file to
"filename.bak"; the modified file gets the original filename.
Change '-pi.bak' to '-pi' if you don't need backup copies. (Note
the use of s||| instead of s/// here, and in the scripts below.
The vertical bars in the 's' command lets you replace '/some/path'
with '/another/path', accommodating slashes in the LHS and RHS.)

4.4.2. - Unix solution

For all files in a single directory, assuming they end with *.txt
and you have no files named "[anything].txt.bak" already, use a
shell script:

#! /bin/sh
# Source files are saved as "filename.txt.bak" in case of error
# The '&&' after cp is an additional safety feature
for file in *.txt
do
cp $file $file.bak &&
sed 's|foo|bar|g' $file.bak >$file
done

To do an entire directory tree, use the Unix utility find, like so
(thanks to Jim Dennis for this script):

#! /bin/sh
# filename: replaceall
find . -type f -name '*.txt' -print | while read i
do
sed 's|foo|bar|g' $i > $i.tmp && mv $i.tmp $i
done

This previous shell script recurses through the directory tree,
finding only files in the directory (not symbolic links, which will
be encountered by the shell command "for file in *.txt", above). To
preserve file permissions and make backup copies, use the 2-line cp
routine of the earlier script instead of "sed ... && mv ...". By
replacing the sed command 's|foo|bar|g' with something like

sed "s|$1|$2|g" ${i}.bak > $i

using double quotes instead of single quotes, the user can also
employ positional parameters on the shell script command tail, thus
reusing the script from time to time. For example,

replaceall East West

would modify all your *.txt files in the current directory.