94

> can do it.

echo "text" > file

tee can do it.

echo "test" | tee file

Can sed do it without using either of the above? Is it possible to save the output of a sed command to a file without using either > or tee?

terdon
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Folaht
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  • Please try to find the answer yourself before posting questions here. The first thing we ask of our users is to [search and research](http://unix.stackexchange.com/help/how-to-ask) before posting. All you needed to do was `sed '' file > newfile` and you would have seen that `>` can indeed be used with `sed` just like with any other program. – terdon May 16 '16 at 10:09
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    That's still using the `>` operator. I was interested if there were a sed command that could be used instead. But I'll delete this question if it's so bad. – Folaht May 16 '16 at 10:29
  • Ah, right. OK, that's a very different question. Since you accepted the `sed -i` answer, I'll edit your question and clarify what you're after. – terdon May 16 '16 at 10:34
  • I accepted "`sed `is not meant for data redirection as `tee` and `>` (are) meant to be". – Folaht May 16 '16 at 10:51

3 Answers3

133

tee and > can be used for data redirection because these are meant to be used for data redirection in linux.

sed on the other hand is a stream editor. sed is not meant for data redirection as tee and > meant to be. However you can use conjunction of commands to do that.

use tee or > with sed

sed 's/Hello/Hi/g' file-name | tee file

or

sed 's/Hello/Hi/g' file-name > file

use sed with -i option

sed -i 's/Hello/Hi/g' file-name

the last one does not redirect, instead it will make changes in the file itself.

ankidaemon
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    Thanks. You understood my question. So the answer is no. I thought `sed` on it's own maybe could do it, because it's also capable of creating backup files with the `-i.bak` option. – Folaht May 16 '16 at 10:56
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    Correct. Also -i.bak is not a fixed option, you can use any extension, which you would like your backup file to have. for ex. -i.log will also work. :) – ankidaemon May 16 '16 at 11:24
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    I just like to add that was actually looking for `echo "test" | dd of=file status=none`, suppressing an echo's output without using the obscure output redirection `2> /dev/null`, but instead asked for sed's limitations. I was really impressed by sed's abilities as it's capable of appending lines in file, giving me the impression that sed could do anything tee could do and more. – Folaht May 16 '16 at 11:26
  • Doesn't work with `-i`: `sed: 1: "pubspec.yaml": extra characters at the end of p command`. My command: `sed -i 's/version:.*/version: 0.0.11+4/g' pubspec.yaml` – Rebar Jun 03 '21 at 22:40
  • The last option will not create the file, unfortunately – Ari Aug 31 '21 at 03:51
  • instead it is modifying the current file @Ari – emrcftci Jan 01 '22 at 16:53
  • Becareful with `sed 's/Hello/Hi/g' file-name > file` if `file-name == file` refer to this [answer](https://stackoverflow.com/a/47198627/7813311) – Animeta May 11 '22 at 16:50
14

sed has the w command that might do what you require:

w filename

Write the current pattern space to filename.

sed 'w file' on its own will have the same effect as tee file. If there are other sed commands, put the w last:

sed 's/This/That/;w file'

However, this won't be affected by the -n/--quiet/--silent option. That only suppresses the content that would otherwise have gone to standard output.

JigglyNaga
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4

As ankidaemon correctly pointed out how we can save sed output to a file. I would like to add that if we are performing some operations on a file i.e replace and would like to save the output to the same file. There is a -i flag in sed which makes inplace edits possible. This however creates a backup file in the process if a suffix is provided as argument. If that's not needed, that can be done by just passing empty filename or nothing to -i flag.

Example: sed -i "s/from/to/" file is inplace changing the file.

camel
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Waqar Ahmed
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