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Replace \n by \r when line (comming from a pipe) contains pattern with GNU sed

I want to use with GNU sed to replace \n by \r when each line (comming from a pipe) begins with a specified pattern but my sed command does not seem to work :

$ cat mpv_all.log | sed -z '/^AV:/s/\n/\r/g'

Can you please help me ?

Solution

  • The issue is that -z causes the whole file to be read in at once. Consequently, ^AV: only matches if the file starts with AV:. You probably want to match AV: on each line. In that case, try:

    sed -Ez ':a; s/((^|[\n\r])AV:[^\n\r]*)\n/\1\r/g ;ta' mpv_all.log

    How it works:

    • -E turns on Extended Regular Expressions.

    • :a defines label a.

    • s/((^|[\n\r])AV:[^\n\r]*)\n/\1\r/g replaced \n with \r at the end of any line that starts with AV:.

    • ta tells sed to go back to label a if the previous substitute command resulted in any changes. This is necessary because patterns could overlap and the g modifier to the s command does not do overlaps.