extract substring (filename) with bash/grep/awk/etc

Question

I have a console output process string like this:

plex     24029 33.3  3.4 330284 63656 ?        Sl   22:37   6:01 /volume1/@appstore/Plex Media Server/Plex Transcoder -codec:0 mpeg2video -codec:1 ac3 -i /volume1/video/classic/Now We've Seen It All!.1976.mkv -filter_complex [0:0]yadif[0];[0]scale=w=768:h=576[1];[1]format=pix_fmts=yuv420p|nv12[2] -filter_complex [0:1] aresample=async=1:ocl='stereo':osr=48000[3] -map [2] -metadata:s:0 language=eng -codec:0 libx264 -crf:0 16 -maxrate:0 7752k -bufsize:0 15504k -r:0 25 -preset:0 veryfast -x264opts:0 subme=1:me_range=4:rc_lookahead=10:me=hex:8x8dct=0:partitions=none -force_key_frames:0 expr:gte(t,0+n_forced*5) -map [3] -metadata:s:1 language=rus -codec:1 aac -b:1 256k -segment_format mpegts -f ssegment -individual_header_trailer 0 -segment_time 5 -segment_start_number 0 -segment_copyts 1 -segment_time_delta 0.0625 -segment_list http://127.0.0.1:32400/video/:/transcode/session/vgh38cdsdmd70euan70xdqh8/cf3a3188-52f9-4b26-8b63-1c348a7c9348/seglist -segment_list_type csv -segment_list_size 2147483647 -segment_list_separate_stream_times 1 -max_delay 5000000 -avoid_negative_ts disabled -map_metadata -1 -map_chapters -1 media-%05d.ts -start_at_zero -copyts -vsync cfr -y -nostats -loglevel quiet -loglevel_plex error -progressurl http://127.0.0.1:32400/video/:/transcode/session/vgh38cdsdmd70euan70xdqh8/cf3a3188-52f9-4b26-8b63-1c348a7c9348/progress

How can I easily extract this filename /volume1/video/classic/Now We've Seen It All!.1976.mkv?

Path and file extensions can be different (.avi,.mkv,.mov,.mpeg).

Answer 1

Assuming the arguments are always in the same order:

grep -oP '(?<=-i ).*?(?= -filter_complex)'

Explanation:

• -o - Print only the matching part of the line
• -P - Use Perl extensions
• (?<=-i ) - Lookbehind for -i
• .*? - Match zero or more characters, non-greedily
• (?= -filter_complex) - Lookahead for -filter_complex

Answer 2

You can filter out the string between “-i ” and “ -filter_complex” with:

sed 's/.*-i \(.*\) -filter_complex.*/\1/'

It saves the string between these two as group 1 and replaces the whole line by it.

Example run

$ echo "plex     24029 33.3  3.4 330284 63656 ?        Sl   22:37   6:01 /volume1/@appstore/Plex Media Server/Plex Transcoder -codec:0 mpeg2video -codec:1 ac3 -i /volume1/video/classic/Now We've Seen It All"'!'".1976.mkv -filter_complex" | sed 's/.*-i \(.*\) -filter_complex.*/\1/'
/volume1/video/classic/Now We've Seen It All!.1976.mkv

Answer 3

It's not easy and error-prone without using a proper options parser such as getopts but you could try using ack-grep like that:

ps ... | ack -o '\-i .+?(\-|$)' | sed 's,^-i ,,' | sed 's,\-$,,'

You can also use GNU grep experimental -P option:

ps ... | grep -oP '\-i .+?(\-|$)' | sed 's,^-i ,,' | sed 's,\-$,,'