My data as following:
P04637 1A1U 1AIE 1C26 1DT7 1GZH 1H26 1HS5 1JSP 1KZY 1MA3 1OLG 1OLH 1PES 1PET 1SAE 1SAF 1SAK 1SAL 1TSR 1TUP 1UOL 1XQH 1YC5 1YCQ But I want as following:
P04637 1A1U P04637 1C26 P04637 1AIE P04637 1DT7 P04637 1XQH P04637 1MA3 P04637 1PES P04637 1SAE This prints the first field and then every subsequent field until end of the line.
$ awk '{for (i=2;i<=NF;i++) print $1,$i}' file P04637 1A1U P04637 1AIE P04637 1C26 P04637 1DT7 P04637 1GZH P04637 1H26 P04637 1HS5 P04637 1JSP P04637 1KZY P04637 1MA3 P04637 1OLG P04637 1OLH P04637 1PES P04637 1PET P04637 1SAE P04637 1SAF P04637 1SAK P04637 1SAL P04637 1TSR P04637 1TUP P04637 1UOL P04637 1XQH P04637 1YC5 P04637 1YCQ To get exactly what OP request, no more, no less:
awk '{print $1,$2 RS $1,$4 RS $1,$3 RS $1,$5 RS $1,$23 RS $1,$11 RS $1,$14 RS $1,$16}' file P04637 1A1U P04637 1C26 P04637 1AIE P04637 1DT7 P04637 1XQH P04637 1MA3 P04637 1PES P04637 1SAE 
Another approach with awk:
awk 'NR==1 {a=$1; next} {print a,$1}' RS=" " file By setting RS=" " we define the line separator as space. This way, we will fetch every time a different record.
NR==1 means while reading the first record. There, we store the first value. From that point, we keep writing the saved value + current one.
It returns:
P04637 1A1U P04637 1AIE P04637 1C26 P04637 1DT7 P04637 1GZH P04637 1H26 P04637 1HS5 P04637 1JSP P04637 1KZY P04637 1MA3 P04637 1OLG P04637 1OLH P04637 1PES P04637 1PET P04637 1SAE P04637 1SAF P04637 1SAK P04637 1SAL P04637 1TSR P04637 1TUP P04637 1UOL P04637 1XQH P04637 1YC5 P04637 1YCQ OFS, but leave an empty line. this is better.
perl -lane '$v=shift @F; print "$v $_" for @F' file 
perl -lane 'print "$F[0] $_" for(@F[1..$#F])' Neither Perl nor Awk is required for this job. Bash is enough:
{ IFS=' ' read -r -a A ; for I in ${A[@]:1} ; do echo ${A[0]} $I ; done ; } <<<'P04637 1A1U 1AIE 1C26 1DT7 1GZH 1H26 1HS5 1JSP 1KZY 1MA3 1OLG 1OLH 1PES 1PET 1SAE 1SAF 1SAK 1SAL 1TSR 1TUP 1UOL 1XQH 1YC5 1YCQ' P04637 1A1U P04637 1AIE P04637 1C26 ... All you need is already here:
As a perl script:
use warnings; use strict; open my $input, '<', 'in.txt' or die "$!"; while (<$input>){ my @split = split; my $spacer = shift @split; print "$spacer $_\n" foreach @split; } Prints:
P04637 1A1U P04637 1AIE P04637 1C26 P04637 1DT7 P04637 1GZH ... Just realize the original question is asking to export randomly
awk 'BEGIN{srand($RANDOM)} { split($0,a,FS); for (i=2;i<=NF;i++) { while (1) { s=int(rand()*(NF-1)+2) if (a[s]!="") {print $1,a[s];delete a[s];break} } } }' file result
P04637 1C26 P04637 1H26 P04637 1DT7 P04637 1HS5 P04637 1AIE P04637 1GZH P04637 1A1U 
awk '{for(i=2;i<=NF;i++)print $1,$i}' file | sort -R
14? And $RANDOM will be equal to the empty string "" I think..