Linux Sed -e参数

Question

I have the following command in my backup rotate script to remove old backups. It works as it ensure the latest backup is retained.

ls -t | sed -e '1,1d' | xargs -d '\n' rm

I'm unsure of the sed -e argument is doing though. When I check man sed I get:

-e script, --expression=script

  add the script to the commands to be executed 

I can't find details of what my current script argument '1,1d' is attempting to do. Can anyone help?

Answer 1

d elete lines 1 to 1 . It just removes the first line.

For testing, type:

seq 10

vs.

seq 10 | sed -e '1,1d'

Answer 2

-e script is adding the script to the sed-command-list. script is used here as synonym for string, in difference to script-file in the option -f script-file . That's why the argument is usually put into quotes (which could be omitted here). The script/string may inlcude a sequence of commands.

You may use more then one -e '<sed-cmd>' , which are then applied to the input line in sequence. For example sed -e 's/kitty/cat/g' -e 's/cat/lion/g' . Sometimes it is easier to understand where all the lions came from.

d is one of the commands which accept address ranges. 1,1 is the address range, here from line 1 to line1, which could be shortened to 1d