try

sed -i '/PLACEHOLDER/ r TestOutput.txt' SQLInput.txt

where

• -i edit in place
• /PLACEHOLDER/ search for pattern
• r TestOutput.txt read file

note that /PLACEHOLDER/ is not deleted.

to have it deleted

sed -i -e '/PLACEHOLDER/ r TestOutput.txt' -e /PLACEHOLDER/d SQLInput.txt

try

sed -i '/PLACEHOLDER/ r TestOutput.txt' SQLInput.txt

where

• -i edit in place
• /PLACEHOLDER/ search for pattern
• r TestOutput.txt read file

note that /PLACEHOLDER/ is not deleted.

to have it deleted

sed -i -e '/PLACEHOLDER/ r TestOutput.txt' -e s/PLACEHOLDER// SQLInput.txt

where

• -e /PLACEHOLDER/d will delete entire line with PLACEHOLDER
• -e s/PLACEHOLDER// will delete PLACEHOLDER string

try

sed -i '/PLACEHOLDER/ r TestOutput.txt' SQLInput.txt

where

• -i edit in place
• /PLACEHOLDER/ search for pattern
• r TestOutput.txt read file

note that /PLACEHOLDER/ is not deleted.

try

sed -i '/PLACEHOLDER/ r TestOutput.txt' SQLInput.txt

where

• -i edit in place
• /PLACEHOLDER/ search for pattern
• r TestOutput.txt read file

note that /PLACEHOLDER/ is not deleted.

to have it deleted

sed -i -e '/PLACEHOLDER/ r TestOutput.txt' -e /PLACEHOLDER/d SQLInput.txt