SED examples
Using back references to append text to each line
Section titled “Using back references to append text to each line”To appending the string EXTRA TEXT to each line
sed -e 's/\(.*\)/\1EXTRA TEXT/'Note the backslash before the brackets.
\1 is the back reference to the first group (only 1 group in this case, which has matched the whole line).
Delete all occurrences of 4 consecutive digits
Section titled “Delete all occurrences of 4 consecutive digits”sed -e 's/[0-9]\{4\}//g'Switch or swap 2 words around
Section titled “Switch or swap 2 words around”sed -e 's/\(.*\)\s\(.*\)/\2 \1/'Extended regular expressions
Section titled “Extended regular expressions”Use the -r switch to turn on extended regular expression. This allows you to use symbols such as
? for zero or one match.
$ echo abcd | sed -e 's/ab?//'abcd$ echo abcd | sed -r -e 's/ab?//'cd