Dash, command substitution not inserting newline?
Clash Royale CLAN TAG#URR8PPP up vote
1
down vote
favorite
Basically, this is the issue:
$ echo Hello"$(printf 'n')"World
HelloWorld
What did I overlook ?
command-line dash-shell
asked Jun 4 at 23:27
Sergiy Kolodyazhnyy
63.8k9127273
add a comment |Â
up vote
1
down vote
favorite
Basically, this is the issue:
$ echo Hello"$(printf 'n')"World
HelloWorld
What did I overlook ?
command-line dash-shell
asked Jun 4 at 23:27
Sergiy Kolodyazhnyy
63.8k9127273
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
Basically, this is the issue:
$ echo Hello"$(printf 'n')"World
HelloWorld
What did I overlook ?
command-line dash-shell
asked Jun 4 at 23:27
Sergiy Kolodyazhnyy
63.8k9127273
Basically, this is the issue:
$ echo Hello"$(printf 'n')"World
HelloWorld
What did I overlook ?
command-line dash-shell
asked Jun 4 at 23:27
Sergiy Kolodyazhnyy
63.8k9127273
asked Jun 4 at 23:27
Sergiy Kolodyazhnyy
63.8k9127273
asked Jun 4 at 23:27
Sergiy Kolodyazhnyy
63.8k9127273
asked Jun 4 at 23:27
Sergiy Kolodyazhnyy
63.8k9127273
63.8k9127273
add a comment |Â
add a comment |Â
1 Answer
1
active
oldest
votes
up vote
2
down vote
accepted
This behavior is actually part of the POSIX specification for command substitution:
The shell shall expand the command substitution by executing command
in a subshell environment (see Shell Execution Environment) and
replacing the command substitution (the text of command plus the
enclosing "$()" or backquotes) with the standard output of the
command, removing sequences of one or more characters at the
end of the substitution. Embedded characters before the end
of the output shall not be removed; however, they may be treated as
field delimiters and eliminated during field splitting, depending on
the value of IFS and quoting that is in effect. If the output contains
any null bytes, the behavior is unspecified.
So the normal quoting rule "$(...)" only preserves non-trailing newlines.
Some suggestions for preserving trailing newlines are given in shell: keep trailing newlines ('n') in command substitution
See also When printing a variable that contains newlines, why is the last newline stripped? for discussion of the rationale behind the specification.
answered Jun 4 at 23:43
steeldriver
62k1196163
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
accepted
This behavior is actually part of the POSIX specification for command substitution:
The shell shall expand the command substitution by executing command
in a subshell environment (see Shell Execution Environment) and
replacing the command substitution (the text of command plus the
enclosing "$()" or backquotes) with the standard output of the
command, removing sequences of one or more characters at the
end of the substitution. Embedded characters before the end
of the output shall not be removed; however, they may be treated as
field delimiters and eliminated during field splitting, depending on
the value of IFS and quoting that is in effect. If the output contains
any null bytes, the behavior is unspecified.
So the normal quoting rule "$(...)" only preserves non-trailing newlines.
Some suggestions for preserving trailing newlines are given in shell: keep trailing newlines ('n') in command substitution
See also When printing a variable that contains newlines, why is the last newline stripped? for discussion of the rationale behind the specification.
answered Jun 4 at 23:43
steeldriver
62k1196163
add a comment |Â
up vote
2
down vote
accepted
This behavior is actually part of the POSIX specification for command substitution:
The shell shall expand the command substitution by executing command
in a subshell environment (see Shell Execution Environment) and
replacing the command substitution (the text of command plus the
enclosing "$()" or backquotes) with the standard output of the
command, removing sequences of one or more characters at the
end of the substitution. Embedded characters before the end
of the output shall not be removed; however, they may be treated as
field delimiters and eliminated during field splitting, depending on
the value of IFS and quoting that is in effect. If the output contains
any null bytes, the behavior is unspecified.
So the normal quoting rule "$(...)" only preserves non-trailing newlines.
Some suggestions for preserving trailing newlines are given in shell: keep trailing newlines ('n') in command substitution
See also When printing a variable that contains newlines, why is the last newline stripped? for discussion of the rationale behind the specification.
answered Jun 4 at 23:43
steeldriver
62k1196163
add a comment |Â
up vote
2
down vote
accepted
up vote
2
down vote
accepted
This behavior is actually part of the POSIX specification for command substitution:
The shell shall expand the command substitution by executing command
in a subshell environment (see Shell Execution Environment) and
replacing the command substitution (the text of command plus the
enclosing "$()" or backquotes) with the standard output of the
command, removing sequences of one or more characters at the
end of the substitution. Embedded characters before the end
of the output shall not be removed; however, they may be treated as
field delimiters and eliminated during field splitting, depending on
the value of IFS and quoting that is in effect. If the output contains
any null bytes, the behavior is unspecified.
So the normal quoting rule "$(...)" only preserves non-trailing newlines.
Some suggestions for preserving trailing newlines are given in shell: keep trailing newlines ('n') in command substitution
See also When printing a variable that contains newlines, why is the last newline stripped? for discussion of the rationale behind the specification.
answered Jun 4 at 23:43
steeldriver
62k1196163
This behavior is actually part of the POSIX specification for command substitution:
The shell shall expand the command substitution by executing command
in a subshell environment (see Shell Execution Environment) and
replacing the command substitution (the text of command plus the
enclosing "$()" or backquotes) with the standard output of the
command, removing sequences of one or more characters at the
end of the substitution. Embedded characters before the end
of the output shall not be removed; however, they may be treated as
field delimiters and eliminated during field splitting, depending on
the value of IFS and quoting that is in effect. If the output contains
any null bytes, the behavior is unspecified.
So the normal quoting rule "$(...)" only preserves non-trailing newlines.
Some suggestions for preserving trailing newlines are given in shell: keep trailing newlines ('n') in command substitution
See also When printing a variable that contains newlines, why is the last newline stripped? for discussion of the rationale behind the specification.
answered Jun 4 at 23:43
steeldriver
62k1196163
answered Jun 4 at 23:43
steeldriver
62k1196163
answered Jun 4 at 23:43
steeldriver
62k1196163
answered Jun 4 at 23:43
steeldriver
62k1196163
62k1196163
add a comment |Â
add a comment |Â
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