compare:  
```
cat raw_expression.txt | head
cat raw_expression.txt | awk -F"\t" '{if(NR==1) $1="NAME"FS$1}1' OFS="\t" | head 
```
$1 is the first field for each line.  
$1="NAME" FS $1  assigns NAME to the first field and seperate by a field seprator (FS), which is a tab.  
1 is always **TRUE**, so awk prints out the rest of the lines.

then, add a second column with a dummy "na":

`awk -F"\t" '{$1=$1FS"na"}1' OFS="\t"`

How many probes in the file?  
`echo "$(cat raw_expression.txt| wc -l)-1" | bc`  
**22277**

bc is a linux command calculator

How many samples in the file?  
`cat raw_expression.txt | awk '{print NF;exit}'`    
**14 samples**.  
after reading the first line and printing out the column number exit awk.

Add two lines in the beginning of the file:
```
cat raw_expression.txt | \
| awk -F"\t" '{if(NR==1) $1="NAME"FS$1}1' OFS="\t" \
| awk -F"\t" '{$1=$1FS"na"}1' OFS="\t" \
| awk 'BEGIN{print "#1.2""\n"22277"\t"14}1' > raw_experssion.gct
```