When I hit a certain Web API, the date information in the CSV data that was spit out was a serial number (why?), So I made a script to convert a specific column of CSV file with awk. As the execution environment, I used Kali with WSL of Windows 10 Pro.
test.sh
#~ Omitted
cat ${output_dir}/tmp.csv | awk '{FS=",";OFS=","} NR>1{ $2=strftime("%Y-%m-%d",
substr($2, 0, 10)) } 1' > ${output_dir}/result.csv
#Omitted ~
It seems that it worked for the time being.
tmp.csv
No,Date,description,
1,1273645330000,TEST,
～
↓
result.csv
No,Date,description,
1,2010-05-12,TEST,
～
WSL
$ echo 1 2 | awk '{print $1}'
1
$ echo 1 2 | awk '{print $1} 1'
1
1 2
$ echo 1 2 | awk '{print $1} 0'
1
$ echo 1 2 | awk '{print $0}'
1 2
$ echo 1 2 | awk '{print}'
1 2
$ echo 1 2 | awk '1'
1 2
$ echo 1 2 | awk '{print $1} true'
1
$ echo 1 2 | awk '{print $1} false'
1
A function that converts a time stamp into a character string that is easy for humans to understand and returns it. This function seems to be the same as ANSI's C standard library.
strftime function
strftime([format [, timestamp]])
| Conversion specification character | Contents |
|---|---|
| %Y | 4-digit year including the century part. |
| %m | Month(Decimal notation).. Specify from 01 to 12. |
| %d | Monthly total date(Decimal notation).. Specify from 01 to 31. |
A function that returns a substring of length length starting from the startth character in string.
substr(string, start [, length])
In this script, I redirected the original CSV data to a new CSV file, Writing to overwrite the original CSV file as shown below did not work. Since the original CSV file is locked with awk, can't it be overwritten?
test.sh
#1
awk '{FS=",";OFS=","} NR>1{ $2=strftime("%Y-%m-%d",
substr($2, 0, 10)) }1' ${output_dir}/tmp.csv > ${output_dir}/tmp.csv
#2
$(awk '{FS=",";OFS=","} NR>1{ $2=strftime("%Y-%m-%d",
substr($2, 0, 10)) }1' ${output_dir}/tmp.csv) > ${output_dir}/tmp.csv
** $ () ** is called "command substitution (posix spec)" and seems to call the subshell. .. You can do the same thing by enclosing it in backticks (``), but it seems that you can nest it.
In the end, the following questions remained, but the goal of returning the serial number in the CSV was achieved. I was able to implement the processing I wanted to do, but it feels like I won the game and lost the game lol If you know the following, I would appreciate it if you could teach me m (_ _) m
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