Gnu sed, will the p command appends a newline when printing?
root@u1804:~# sed --version
sed (GNU sed) 4.5
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Jay Fenlason, Tom Lord, Ken Pizzini,
and Paolo Bonzini.
GNU sed home page: <https://www.gnu.org/software/sed/>.
General help using GNU software: <https://www.gnu.org/gethelp/>.
E-mail bug reports to: <bug-sed@gnu.org>.
root@u1804:~#
I'm new to sed and I created below sed's workflow based on my understanding (correct me if you find anything wrong).
So it seems the default auto printing of the pattern space will always include a newline at the end. My question is, will p includes a newline, too? I have below examples.
root@u1804:~# seq 3 | sed -rn 'p'
1
2
3
root@u1804:
Here the newline at the end of each number is added by sed itself (see the diagram "adds back newline to pattern space"). So it seems p will not append a newline. However, see below example.
root@u1804:~# seq 3 | sed -rn 'x;p;x;p'
1
2
3
root@u1804:~#
Here x exchange pattern space with hold space, which will result in an empty pattern space. Now p applies to the pattern space (nothing in it) should print nothing. But based on the result, it seems here p prints a newline. To me it seems this is inconsistent behavior. Can anyone help to explain, please?
sed
asked 5 mins ago
Ogrish ManOgrish Man
5151415
add a comment |
root@u1804:~# sed --version
sed (GNU sed) 4.5
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Jay Fenlason, Tom Lord, Ken Pizzini,
and Paolo Bonzini.
GNU sed home page: <https://www.gnu.org/software/sed/>.
General help using GNU software: <https://www.gnu.org/gethelp/>.
E-mail bug reports to: <bug-sed@gnu.org>.
root@u1804:~#
I'm new to sed and I created below sed's workflow based on my understanding (correct me if you find anything wrong).
So it seems the default auto printing of the pattern space will always include a newline at the end. My question is, will p includes a newline, too? I have below examples.
root@u1804:~# seq 3 | sed -rn 'p'
1
2
3
root@u1804:
Here the newline at the end of each number is added by sed itself (see the diagram "adds back newline to pattern space"). So it seems p will not append a newline. However, see below example.
root@u1804:~# seq 3 | sed -rn 'x;p;x;p'
1
2
3
root@u1804:~#
Here x exchange pattern space with hold space, which will result in an empty pattern space. Now p applies to the pattern space (nothing in it) should print nothing. But based on the result, it seems here p prints a newline. To me it seems this is inconsistent behavior. Can anyone help to explain, please?
sed
asked 5 mins ago
Ogrish ManOgrish Man
5151415
add a comment |
root@u1804:~# sed --version
sed (GNU sed) 4.5
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Jay Fenlason, Tom Lord, Ken Pizzini,
and Paolo Bonzini.
GNU sed home page: <https://www.gnu.org/software/sed/>.
General help using GNU software: <https://www.gnu.org/gethelp/>.
E-mail bug reports to: <bug-sed@gnu.org>.
root@u1804:~#
I'm new to sed and I created below sed's workflow based on my understanding (correct me if you find anything wrong).
So it seems the default auto printing of the pattern space will always include a newline at the end. My question is, will p includes a newline, too? I have below examples.
root@u1804:~# seq 3 | sed -rn 'p'
1
2
3
root@u1804:
Here the newline at the end of each number is added by sed itself (see the diagram "adds back newline to pattern space"). So it seems p will not append a newline. However, see below example.
root@u1804:~# seq 3 | sed -rn 'x;p;x;p'
1
2
3
root@u1804:~#
Here x exchange pattern space with hold space, which will result in an empty pattern space. Now p applies to the pattern space (nothing in it) should print nothing. But based on the result, it seems here p prints a newline. To me it seems this is inconsistent behavior. Can anyone help to explain, please?
sed
asked 5 mins ago
Ogrish ManOgrish Man
5151415
root@u1804:~# sed --version
sed (GNU sed) 4.5
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Jay Fenlason, Tom Lord, Ken Pizzini,
and Paolo Bonzini.
GNU sed home page: <https://www.gnu.org/software/sed/>.
General help using GNU software: <https://www.gnu.org/gethelp/>.
E-mail bug reports to: <bug-sed@gnu.org>.
root@u1804:~#
I'm new to sed and I created below sed's workflow based on my understanding (correct me if you find anything wrong).
So it seems the default auto printing of the pattern space will always include a newline at the end. My question is, will p includes a newline, too? I have below examples.
root@u1804:~# seq 3 | sed -rn 'p'
1
2
3
root@u1804:
Here the newline at the end of each number is added by sed itself (see the diagram "adds back newline to pattern space"). So it seems p will not append a newline. However, see below example.
root@u1804:~# seq 3 | sed -rn 'x;p;x;p'
1
2
3
root@u1804:~#
Here x exchange pattern space with hold space, which will result in an empty pattern space. Now p applies to the pattern space (nothing in it) should print nothing. But based on the result, it seems here p prints a newline. To me it seems this is inconsistent behavior. Can anyone help to explain, please?
sed
sed
asked 5 mins ago
Ogrish ManOgrish Man
5151415
asked 5 mins ago
Ogrish ManOgrish Man
5151415
asked 5 mins ago
Ogrish ManOgrish Man
5151415
asked 5 mins ago
Ogrish ManOgrish Man
5151415
asked 5 mins ago
Ogrish ManOgrish Man
5151415
5151415
add a comment |
add a comment |
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