merge blocks of four line into one line [duplicate]

Using paste

    $ paste -d' ' - - - - <file
    16:20:03 Buy DRIP AMEX 500 13,51 USD
    16:05:10 Sell SQ NYSE 100 36,32 USD
    15:48:52 Sell NXTD Nasdaq 500 4,99 USD
    15:48:52 Sell NXTD Nasdaq 500 4,99 USD
    15:46:07 Buy SOXL AMEX 50 147,7209 USD
    15:40:20 Buy TEUM AMEX 1 700 1,36 USD
    15:40:19 Buy TEUM AMEX 300 1,36 USD

Using sed

    $ sed 'N;N;N; s/\n/ /g' file
    16:20:03 Buy DRIP AMEX 500 13,51 USD
    16:05:10 Sell SQ NYSE 100 36,32 USD
    15:48:52 Sell NXTD Nasdaq 500 4,99 USD
    15:48:52 Sell NXTD Nasdaq 500 4,99 USD
    15:46:07 Buy SOXL AMEX 50 147,7209 USD
    15:40:20 Buy TEUM AMEX 1 700 1,36 USD
    15:40:19 Buy TEUM AMEX 300 1,36 USD

Using awk

    $ awk '{line=line " " $0} NR%4==0{print substr(line,2); line=""}' file
    16:20:03 Buy DRIP AMEX 500 13,51 USD
    16:05:10 Sell SQ NYSE 100 36,32 USD
    15:48:52 Sell NXTD Nasdaq 500 4,99 USD
    15:48:52 Sell NXTD Nasdaq 500 4,99 USD
    15:46:07 Buy SOXL AMEX 50 147,7209 USD
    15:40:20 Buy TEUM AMEX 1 700 1,36 USD
    15:40:19 Buy TEUM AMEX 300 1,36 USD

Perl solution

perl -pe 's/\n/ / if $. % 4' < file

• -p reads the input line by line, processes it and prints it back to the output;
• $. contains the input line number
• s/\n/ / replaces a newline by a space
• % is the modulo operator, so the condition reads "if the line number isn't divisible by four"

The easiest solution is probably with ex, the non-visual form of vi (which is specified by POSIX).

printf '%s\n' 'g/^/j4' x | ex input.txt

Equivalently:

printf 'g/^/j4\nx\n' | ex input.txt

Explanation:

The printf command just produces the following output, which are commands to ex:

g/^/j4
x

The x command means to save and exit. Replace with %p if you want to print the modified file to standard output and not save changes (good for testing).

g is the global command and takes a regex (in this case /^/ which will of course match on every line) and then a command. The command is run on every line matched by the regex.

j4 means to join the current line with the following three lines. Spaces are put in between when joining.

You can also fire up vi and just type 4J and then j to go down a line and then type ., and then j to go down a line and then ., etc. But with the ex form any left-over lines at the end of the file (less than four) will be joined together; with the J command in vi this is not the case.

$ awk '{printf $0 (NR%4?" ":"\n")}' file1
16:20:03 Buy DRIP AMEX 500 13,51 USD
16:05:10 Sell SQ NYSE 100 36,32 USD
15:48:52 Sell NXTD Nasdaq 500 4,99 USD
15:48:52 Sell NXTD Nasdaq 500 4,99 USD
15:46:07 Buy SOXL AMEX 50 147,7209 USD
15:40:20 Buy TEUM AMEX 1 700 1,36 USD
15:40:19 Buy TEUM AMEX 300 1,36 USD