보낸 사람 bash manpage
:
Duplicating File Descriptors
The redirection operator
[n]<&word
is used to duplicate input file descriptors. If word expands to one or
more digits, the file descriptor denoted by n is made to be a copy of
that file descriptor. If the digits in word do not specify a file
descriptor open for input, a redirection error occurs. If word evalu‐
ates to -, file descriptor n is closed. If n is not specified, the
standard input (file descriptor 0) is used.
The operator
[n]>&word
is used similarly to duplicate output file descriptors. If n is not
specified, the standard output (file descriptor 1) is used. If the
digits in word do not specify a file descriptor open for output, a re‐
direction error occurs. As a special case, if n is omitted, and word
does not expand to one or more digits, the standard output and standard
error are redirected as described previously.
나는 몇 가지 디버그를했다 strace
:
sudo strace -f -s 200 -e trace=dup2 bash redirect.sh
의 경우 3<&1
:
dup2(3, 255) = 255
dup2(1, 3) = 3
의 경우 3>&1
:
dup2(1, 3) = 3
의 경우 2>&1
:
dup2(1, 2) = 2
stdout을 파일 설명자 3에 복제 3<&1
하는 것과 정확히 동일한 것으로 보입니다 3>&1
.
exec 3<&1
점에서 다릅니다3<&1
.