cut file and overwrite file

Asked Feb 11 '22 at 07:18

Active Feb 11 '22 at 07:18

Viewed 22 times

Let's say I have file.txt

water 1
lorem 0
ipsum 0

I cut the last column and redirect output to file itself with this:

cut -d' ' -f 1 file.txt > file.txt

I expect current content of file.txt is

water
lorem
ipsum

However, I got blank file in file.txt

asked Feb 11 '22 at 07:18

Specifically, [this answer about `>`](https://unix.stackexchange.com/a/186126/86440). – Stephen Kitt Feb 11 '22 at 07:31
So I need to create temp_file as buffer and rename temp_file to actuall name file. – Muhammad Ikhwan Perwira Feb 11 '22 at 07:43
3

So the solution for my case is ```cut -d' ' -f1 file.txt> temp && mv temp file.txt``` – Muhammad Ikhwan Perwira Feb 11 '22 at 07:44
or if you have GNU awk: `awk -i inplace '{print $1}' file.txt` – pLumo Feb 11 '22 at 08:02
1

There is a utility for this: `cut -d' ' -f 1 file.txt | sponge file.txt`. `sponge` collects all the output, then writes it to the named file (**no** redirection) *after* the previous program has finished reading it. – Paul_Pedant Feb 11 '22 at 08:10
@Paul_Pedant and it’s mentioned in the linked answer ;-). – Stephen Kitt Feb 11 '22 at 08:12
@StephenKitt It does. I wondered why the OP went with the temp_file solution, though. – Paul_Pedant Feb 11 '22 at 10:49

0 Answers0