Question

I want to delete text after the first colon : (inclusive), or replace it with nothing.

For example, 1:5:30 should be changed into 1. I prefer an awk script to perform this job. But I do not know how to do that. Could you please give me any directions? Thanks in advance.

My data are tab-delimited, and the file looks like there are points in some cells.

1       313     .       T       C       30.11        1:5:30  .       .       .
1       316     .       A       T       30.80        1:5:30  .       0:8:28  .
1       317     .       T       A       31.40        1:5:36  .       0:8:28  .

I tried the following, but I failed with all of them:

sed 's/:*:*//g' mydatafile
sed 's/:[0-9]:[0-9]//g' mydatafile

Answer 1

Bit unclear what the desired output should be, but this is my interpretation, using sed:

$ sed 's/:.*//' input
1   313 .   T   C   30.11   1
1   316 .   A   T   30.80   1
1   317 .   T   A   31.40   1

Using awk:

$ awk -F":" '{print $1}' input
1   313 .   T   C   30.11   1
1   316 .   A   T   30.80   1
1   317 .   T   A   31.40   1

Using Cut:

cut -d":" -f1 input

Using bash:

IFS=':'

while read a b; do
    echo $a
done < input

Alternative interpretation using awk:

$ awk 'BEGIN {OFS="\t"} {sub(/:.*/,"",$7); print}' input
1   313 .   T   C   30.11   1   .   .   .
1   316 .   A   T   30.80   1   .   0:8:28  .
1   317 .   T   A   31.40   1   .   0:8:28  .

3rd and hopefully last update

3rd interpretation using awk:

$ awk 'BEGIN {OFS="\t"} {for (i=1;i<NF;i++){sub(/:.*/,"",$i)}; print}' input
1   313 .   T   C   30.11   1   .   .   .
1   316 .   A   T   30.80   1   .   0   .
1   317 .   T   A   31.40   1   .   0   .