I have a big list of ordered files with name like this (videos)

S1-E18-(Date)-(Title)-(Random numbers).mp4

Here is the example of list


In this case its easy to see that the files S1-E2 and S10-E4 are missing. but if I have a big list then how can I find the missing files. (Leave Season number S1, S2) just need to check E means episode number

The largest existing file's number is S50-E2184 and The Smallest existing file's number is S1-E1

closed as off-topic by karel, N0rbert, dessert, Eric Carvalho, George Udosen Nov 24 '18 at 0:36

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  • Hi! This is a question for stack overflow. People here only really answer questions about Ubuntu directly. – Lewis Smith Nov 21 '18 at 9:51
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    @LewisSmith not really, text processing is very much on topic here in practice. Just look at the numerous posts on AU on the topic. – Jacob Vlijm Nov 21 '18 at 10:10
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    Are the lines/numbers sorted in the file? – Jacob Vlijm Nov 21 '18 at 10:11
  • @JacobVlijm - My apologies. In that case ignore me. – Lewis Smith Nov 21 '18 at 10:22
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    Agreed, @EliShain please clarify if you are looking for a strictly python based solution, or if another language would be acceptable to you. – Jacob Vlijm Nov 21 '18 at 13:35

Using awk:

$ awk -F- '{n = substr($2, 2)} (n - prev) != 1 {for (i = prev + 1; i < n; i++) print i} {prev = n}' input-file
  • -F - sets the field separator to - (so S1, E1, etc. become different fields).
  • Then we extract the episode number (n = substr($2, 2)), by taking everything but the first character from the second field ($2).
  • If the episode number is not the previous episode + 1 ( (n - prev) != 1), we print all the numbers in between.
  • We save the current episode number in prev for the next iteration.

If the output isn't sorted, split up the extraction and check to insert a sort in between:

awk -F- '{print substr($2, 2)}' input-file | sort -n | awk '{n=$1} (n - prev) != 1 {for (i = prev + 1; i < n; i++) print i} {prev = n}'
  • Mind that the lines aren't sorted (yet) – Jacob Vlijm Nov 22 '18 at 7:42

A bit more straight forward script. The script assumes the last episode exists and extracts its episode number. Then it iterates over [1..last] and check the existence of all episodes in between. Note this would not work for episodes numbered with leading zeroes.


if [ -z "$1" ]; then
    echo "please specify season prefix"

# extract last episode number
last=`ls $1-*.* -1 --reverse | head -n 1 | grep --only-matching "E[[:digit:]+]" | cut -c 2-`

for ((i=1; i<=$last; i++)); do
    if [ ! -f $1-E$i-*.* ]; then
        echo "missing episode $i"

The script takes the season prefix as its first argument, i.e. S1

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