Awk - How to Delete First Column with Field Separator

awk - how to delete first column with field separator

Assuming your original CSV file is named "orig.csv":

awk -F'|' '{print $1 > "newfile"; sub(/^[^|]+\|/,"")}1' orig.csv > tmp && mv tmp orig.csv

awk: change field separator keeping first column as is

Could you please try following, written and tested on shown samples only. This should work with any number of fields too tested it in https://ideone.com/fWgggq

awk '
BEGIN{
  FS="_"
  OFS=","
  print "ID,group1,group2,group3"
}
FNR>1{
  val=$0
  $1=$1
  print val,$0
}'  Input_file

Explanation: Adding detailed explanation for above.

awk '                                   ##Starting awk program from here.
BEGIN{                                  ##Starting BEGIN section of program from here.
  FS="_"                                ##Setting field separator as _ here,
  OFS=","                               ##Setting OFS as comma here.
  print "ID,group1,group2,group3"       ##Printing header as per OP requirement here.
}
FNR>1{                                  ##Checking condition if this is greater than 1st line then do following.
  val=$0                                ##Store current line into var val here.
  $1=$1                                 ##reassign first field to itself so that new OFS which is , is implemented to whole line.
  print val,$0                          ##Printing current new line here.
}'  Input_file                          ##Mentioning Input_file name here.

Unix , Delete first column using awk

Use cut:

cut -d, -f2- file

-d, uses , as delimiter, and -f2- prints fields 2 to last.

Remove first columns delimiter

$ awk '{for(i=1;i<4;i++)sub(/;/,"")}1' file
38528;9;5;8;6
7456;2;2;4;6

How to delete first three columns in a delimited file

@Heng: try:

awk -F"|" '{for(i=4;i<=NF;i++){printf("%s%s",$i,i==NF?"":"|")};print ""}'  Input_file

OR

awk -F"|" '{for(i=4;i<=NF;i++){printf("%s%s",$i,i==NF?"\n":"|")};}'  Input_file

you could re-direct this command's output into a file as per your need.

EDIT:

awk -F"|" 'FNR==1{++e;fi="REPORT_A1_"e;} {for(i=4;i<=NF;i++){printf("%s%s",$i,i==NF?"\n":"|") > fi}}'   Input_file1  Input_file2  Input_file3

Delete first column of csv file

Following awk will be helping you in same.

awk '{sub(/[^,]*/,"");sub(/,/,"")} 1'   Input_file

Following sed may also help you in same.

sed 's/\([^,]*\),\(.*\)/\2/'  Input_file

Explanation:

awk '                 ##Starting awk code here.
{
  sub(/[^,]*/,"")     ##Using sub for substituting everything till 1st occurence of comma(,) with NULL.
  sub(/,/,"")         ##Using sub for substituting comma with NULL in current line.
}
1                     ##Mentioning 1 will print edited/non-edited lines here.
'   Input_file        ##Mentioning Input_file name here.

Remove first column without removing header

All you need is:

awk 'NR>1{sub(/[^\t]*\t/,"")}1' file

awk -cut how to delete second column with field separator

If your Input_file is same as shown sample then following may help you on same:

awk '{sub(/\|\|o\|\|[0-9]+\|\|o\|\|/,"||o||")} 1'  Input_file

Output will be as follows:

'&(||o||lonyfoe||o||Joe||o||Joe||o||Otieno

Remove first columns then leave remaining line untouched in awk

first as ED commented, you have to use FS as field separator in awk.
tab becomes space in your output, because you didn't define OFS.

awk 'BEGIN{FS=OFS="\t"}{$1=$2=$3="";print}' file

this will remove the first 3 fields, and leave rest text "untouched"( you will see the leading 3 tabs). also in output the <tab> would be kept.

awk 'BEGIN{FS=OFS="\t"}{print $4,$5,$6}' file

will output without leading spaces/tabs. but If you have 500 columns you have to do it in a loop, or use sub function or consider other tools, cut, for example.

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