Shell Programming and Scripting

I've a text file whose content needs to be changed every month as below:
For July the content should be below:
FACT_AMT=FACT_AMT_16
for August
FACT_AMT=FACT_AMT_17-FACT_AMT_16
for September
FACT_AMT=FACT_AMT_18-FACT_AMT_17
for October
FACT_AMT=FACT_AMT_19-FACT_AMT_18
For November
FACT_AMT=FACT_AMT_20-FACT_AMT_19
for December
FACT_AMT=FACT_AMT_21-FACT_AMT_20
For January
FACT_AMT=FACT_AMT_22-FACT_AMT_21
For February
FACT_AMT=FACT_AMT_23-FACT_AMT_22
For March
FACT_AMT=FACT_AMT_24-FACT_AMT_23
For April
FACT_AMT=FACT_AMT_25-FACT_AMT_24
For May
FACT_AMT=FACT_AMT_26-FACT_AMT_25
For June
FACT_AMT=FACT_AMT_27-FACT_AMT_26

Could someone provide thoughts?

Thanks,
Bhagat

In Python

Code:

data = open("file.txt").read()
amt, famt = data.split("=") # amt = FACT_AMT, famt = FACT_AMT_16
famt_num = int(famt[-2:]) + 1 #add the last num, eg 16 + 1
newfamt = famt[:-2] + str(famt_num) + "-" + famt # eg FACT_AMT_17-FACT_AMT_16
o = open("file.txt" ,"w") #open file for replacing
print >> o , amt + "=" + newfamt

output:

Code:

FACT_AMT=FACT_AMT_17-FACT_AMT_16

With sh, you can do something like that :

Code:

month=`date +%m`

month_1=`expr $month + 9`
[ $month -lt 7 ] && month_1=`expr $month_1 + 12`
month_2=`expr $month_1 + 1`

line="FACT_AMT=FACT_AMT_${month_1}"
[ $month -ne 7 ] && line="${line}-FACT_AMT_${month_2}"
   
echo ${line} > file.txt

Jean-Pierre.