John, 1234567 Bob, 2839211 Alex, 2817821 Mary, 9371281 I am currently trying to retrieve the first column with the last 4 digits of the second column using sed, so the output should look like this:
John, 4567 Bob, 9211 Alex, 7821 Mary, 1281 This is my command: 's/\(.*,\)\(.*\)//', I think that this command matches the first column until the comma and the second column until the end, but I am unsure on how to continue.
You can use
sed 's/^\([^,]*\), *[0-9]*\([0-9]\{4\}\).*/\1, \2/' file See the online demo.
Details
^ - start of string\([^,]*\) - Group 1: any zero or more chars other than a comma, * - a comma and zero or more spaces[0-9]* - zero or more digits\([0-9]\{4\}\) - Group 2: four digits.* - the rest of the line\1, \2 - The replacement is: Group 1, ,, space and Group 2 value.
Just capture the last four digits of each line and delete any preceding digits:
$ sed 's/[0-9]*\([0-9]\{4\}\)$/\1/' input.txt John, 4567 Bob, 9211 Alex, 7821 Mary, 1281 If using a version of sed that supports POSIX Extended Regular Expressions, it can be cleaned up a bit to
sed -E 's/[0-9]*([0-9]{4})$/\1/' input.txt In case you are ok with awk, could you please try following. Written and tested with shown samples in GNU awk.
awk 'BEGIN{FS=OFS=", "} {$2=substr($2,length($2)-3)} 1' Input_file Explanation: Adding detailed explanation for above.
awk ' ##Starting awk program from here. BEGIN{ ##Starting BEGIN section of this program from here. FS=OFS=", " ##Setting FS and OFS to comma space here. } { $2=substr($2,length($2)-3) ##Getting last 4 digits now in 2nd field here. } 1 ##printing current edited/non-edited line. ' Input_file ##Mentioning Input_file name here. 2nd solution: Adding 1 more solution in case your 2nd column can have mix of digits and other non digits then following may help you.
awk 'BEGIN{FS=OFS=", "} {gsub(/[^0-9]+/,"",$2);$2=substr($2,length($2)-3)} 1' Input_file Explanation: Adding detailed explanation for above.
awk ' ##Starting awk program from here. BEGIN{ ##Starting BEGIN section of this program from here. FS=OFS=", " ##Setting FS and OFS to comma space here. } { gsub(/[^0-9]+/,"",$2) ##Globally substituting everything apart from digits with NULL in 2nd field. $2=substr($2,length($2)-3) ##getting last 4 digits now in 2nd field here. } 1 ##printing current edited/non-edited line. ' Input_file ##Mentioning Input_file name here. Similar to KamilCuk's answer except uses a POSIX character class and anchors the digits to be removed:
sed 's/, [[:digit:]]\{3\}/, /' If the file format is just <text only alphanumeric characters>, <number exactly 7 digits>, you can just remove first 3 digits there are:
sed 's/[0-9][0-9][0-9]//' 
sed 's/[0-9]\{3\}//'
<text>, <number>?,character