Insert multiple lines of text before specific line using Bash

Question

I am trying to insert a few lines of text before a specific line, but keep getting sed errors when I try to add a new line character. My command looks like:

Answer 1

When the lines to be inserted are the result of some command "mycmd" (like cat results.txt or printf "%s\n" line{1..3}), you can do

sed -i 's/Line to insert after/r' <(cmd) file
or 
sed -i 's/Line to insert after/echo "&";cmd/e' file

The last command can be simple modified when you want to insert before some match.

Answer 2

On MacOs I needed a few more things.

• Double backslash after the i
• Empty quotes after the -i to specify no backup file
• Leading backslashes to add leading whitespace
• Trailing double backslashes to add newlines

This code searches for the first instance of </plugins in pom.xml and inserts another XML object immediately preceding it, separated by a newline character.

sed -i '' "/\<\/plugins/ i \\
\            <plugin>\\
\                <groupId>org.apache.maven.plugins</groupId>\\
\                <artifactId>maven-source-plugin</artifactId>\\
\                <executions>\\
\                    <execution>\\
\                        <id>attach-sources</id>\\
\                        <goals>\\
\                            <goal>jar</goal>\\
\                        </goals>\\
\                    </execution>\\
\                </executions>\\
\            </plugin>\\
" pom.xml

Answer 3

This might work for you (GNU sed & Bash):

sed -i $'/Line to insert after/a\line1\\nline2\\nline3' file

Answer 4

For anything other than simple substitutions on individual lines, use awk instead of sed for simplicity, clarity, robustness, etc., etc.

To insert before a line:

awk '
/Line to insert before/ {
    print "Line one to insert"
    print "second new line to insert"
    print "third new line to insert"
}
{ print }
' /etc/directory/somefile.txt

To insert after a line:

awk '
{ print }
/Line to insert after/ {
    print "Line one to insert"
    print "second new line to insert"
    print "third new line to insert"
}
' /etc/directory/somefile.txt

Answer 5

sed -i '/Line to insert after/ i\
Line one to insert\
second new line to insert\
third new line to insert' /etc/directory/somefile.txt

Answer 6

To be POSIX compliant and run in OS X, I used the following (single quoted line and empty line are for demonstration purposes):

sed -i "" "/[pattern]/i\\
line 1\\
line 2\\
\'line 3 with single quotes\`
\\
" <filename>