The proper format of a 'sed' command?

Question

Im trying to rename some files and need help with formatting a proper 'sed' command;

I have a file of movie episodes that looks like this;

SG1_s10e8"Memento Mori"
SG1_s10e9"Company of Thieves"
SG1_s10e10"The Quest"
SG1_s10e11"The Quest Part 2"

and I need to pad the episode # with a '0' like this;

SG1_s10e08"Memento Mori"
SG1_s10e09"Company of Thieves"
SG1_s10e10"The Quest"
SG1_s10e11"The Quest Part 2"

I'm sure sed is the correct tool, im just not real keen with the command syntax.

I would appreciate any help.

score 3 · Accepted Answer · answered Feb 10 '17 at 15:51

3

sed 's/e\([0-9]"[^"]*"\)/e0\1/' file

answered Feb 10 '17 at 15:51

Ed Morton

Can you please explain what the `e` is doing in the expression above? ty – jes516 Feb 10 '17 at 16:56
1

@jes516 have a close look at the input data and the desired output and think about why the `e` is important. – glenn jackman Feb 10 '17 at 17:40

score 1 · Answer 2 · answered Feb 10 '17 at 15:43

1

you could try this:

sed 's/e\([0-9]\)"/e0\1"/'

answered Feb 10 '17 at 15:43

João Miranda

Not bad but it'd fail for `SG1_s10e08"Memento More9"` for example. – Ed Morton Feb 10 '17 at 15:49
No, because it only replaces the first occurrence; that would happen with the g at the end, as in 's///g', but not with 's//'. Right? – João Miranda Feb 10 '17 at 15:53
I had the wrong example at first, edited my comment now with the correct example. sorry. What I'm saying is if `e[0-9]"` does NOT occur in the expected position before the start of the double quoted string but then does occur at the end of the string then the replacement would happen at that wrong location. – Ed Morton Feb 10 '17 at 15:53
1

True. You'd have to add something more, like you did. – João Miranda Feb 10 '17 at 15:57

2 Answers2