Something like: cat template.txt | ruby -e ‘puts STDIN.read.sub(%placeholder%, IO.read(content.txt))’ > output.txt Or: ed

Question

Editorial Team

Asked: May 23, 20262026-05-23T12:51:10+00:00 2026-05-23T12:51:10+00:00

Something like:

cat template.txt | ruby -e 'puts STDIN.read.sub("%placeholder%", IO.read("content.txt"))' > output.txt

Or:

ed template.txt <<EOF
/%placeholder%/d
.r content.txt
w output.txt
EOF

Any alternatives?

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Editorial Team · Answer 1 · 2026-05-23T12:51:10+00:00

Editorial Team

[me@home]$ sed -e '/\$xxx/r content.txt' -e '/\$xxx/d' template.txt 
.,:;-+=_'"`*^?!
.,:;-+=_'"`*^?!
&$%#@|/\()[]{}<>
&$%#@|/\()[]{}<>

The first command searches for $xxx then prints out the contents of content.txt. The second one deletes $xxx.

You can also use a multi-line command, which would be more readable when used in scripts.

sed -e '/\$xxx/{
   r content.txt
   d
}' template.txt

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