Replace a simple string
Example: Change port from 8080 to 9090 in config.ini of a Virgo installation:
sed -i 's/8080/9090/' /virgo/home/configuration/config.ini
Replace a placeholder in a file with a value available as environment variable
Hint: Beware of the other type of quotes to allow the shell to replace the values.
sed -i -r "s/<placeholder>/${ENVIRONMENT_VALUE}/g” planets-configuration.yaml
Add a new item to a multi-line list
Change existing line and append one line after the modified line.
Example: Add JavaSE-1.7 to existing java6-server.profile of a Virgo installation:
sed -i 's/JavaSE-1.6/JavaSE-1.6,\\\n JavaSE-1.7/' /virgo/home/configuration/java6-server.profile.
Remove all lines in a file that match a given pattern and write result into new file
Example: Remove all items containing my pattern and write result in a file named scenario-reduced.data:
sed '/my pattern/d' scenario-alpha.data > scenario-reduced.data
Preprocessing pipeline - filter empty/commented-out lines
First things first, the single steps:
- Filter empty lines and
- remove commented out lines.
Filter empty lines
sed '/^$/d' file_with_empty_lines.data
Filter lines with comments
sed '#.*$/d'
Chaining the single steps
Imaging you want to inspect a data file full of JSON documents (one each line) with empty lines and commented out documents…
sed -e '/^$/d' -e '#.*$/d' scenario-alpha.data | jq
More on this How to chain sed append commands? sed + remove “#” and empty lines with one sed command
If your document contains more than a single document:
while read line; do echo $line | jq -r '.field.innerField'; done < scenario-alpha.data