UNIX for Beginners Questions & Answers

Sample_S1_L001_R1.txt
Sample_S10_L001_R1.txt
Sample_S11_L001_R1.txt

ls *.txt | sed 's/\(.*_S\)\([1-9]_.*\)/mv & \10\2/' | sh

ls *.txt | sed 's/\(.*_\)\(S\)\([0-9]*_\)\(.*\)/mv & MID-\3\1\4/' | sh

MID-01_Sample_L001_R1.txt
MID-10_Sample_L001_R1.txt
MID-11_Sample_L001_R1.txt

ls *.txt | sed -r 'h; s/(.*_S)([1-9]_.*)/\10\2/; s/^(.*_)S([0-9]{2}_)/ MID-\2\1/; H; g; s/\n//; s/^/mv /'

ls *.txt | sed '
s/\(.*_\)S\([0-9][0-9]_\)\(.*\)/mv & MID-\2\1\3/
s/\(.*_\)S\([0-9]_\)\(.*\)/mv & MID-0\2\1\3/
'

ls *.txt | sed '
s/\(.*_\)S\([0-9][0-9]_\)\(.*\)/mv & MID-\2\1\3/
t
s/\(.*_\)S\([0-9]_\)\(.*\)/mv & MID-0\2\1\3/
'

ls *.txt | sed -r 's/^(.*_)S([0-9]{1,2}_)(.*)/mv & MID-0\2\1\3/; s/-0([0-9]{2})/-\1/'