shell script에서 parent,child process 간 특정 변수 공유 관련 질문입니다.

[schoi0@SEL-SCHOI0-D2 tmp]$ tree -p
.
├── [-rw-rw-r--]  a
├── [-rw-rw-r--]  b
├── [-rw-rw-r--]  c
├── [-rw-rw-r--]  d
└── [drwxrwxr-x]  tmp
 
1 directory, 4 files
[schoi0@SEL-SCHOI0-D2 tmp]$ x=$(find ! -type d | while read ent; do x=$(cp $ent tmp/ 2>&1); [ -n "$x" ] && echo "#File:\"$ent\" Error:\"$x\""; done)
[schoi0@SEL-SCHOI0-D2 tmp]$ (IFS=$'#\n'; for err in $x; do [ -n "$err" ] && echo ERROR: $err; done)
[schoi0@SEL-SCHOI0-D2 tmp]$ 
[schoi0@SEL-SCHOI0-D2 tmp]$ tree -p
.
├── [-rw-rw-r--]  a
├── [-rw-rw-r--]  b
├── [-rw-rw-r--]  c
├── [-rw-rw-r--]  d
└── [drwxrwxr-x]  tmp
    ├── [-rw-rw-r--]  a
    ├── [-rw-rw-r--]  b
    ├── [-rw-rw-r--]  c
    └── [-rw-rw-r--]  d
 
1 directory, 8 files
[schoi0@SEL-SCHOI0-D2 tmp]$ x=$(find ! -type d | while read ent; do x=$(cp $ent tmp/ 2>&1); [ -n "$x" ] && echo "#File:\"$ent\" Error:\"$x\""; done)
[schoi0@SEL-SCHOI0-D2 tmp]$ (IFS=$'#\n'; for err in $x; do [ -n "$err" ] && echo ERROR: $err; done)
ERROR: File:"./tmp/d" Error:"cp: './tmp/d' and 'tmp/d' are the same file"
ERROR: File:"./tmp/c" Error:"cp: './tmp/c' and 'tmp/c' are the same file"
ERROR: File:"./tmp/a" Error:"cp: './tmp/a' and 'tmp/a' are the same file"
ERROR: File:"./tmp/b" Error:"cp: './tmp/b' and 'tmp/b' are the same file"
 
[schoi0@SEL-SCHOI0-D2 tmp]$ (IFS=$'#\n'; for err in $x; do [ -n "$err" ] && (IFS=$'"\n'; y=($err); echo Error for the file \"${y[1]}\"; echo "  ${y[3]}".); done)
Error for the file "./tmp/d"
  cp: './tmp/d' and 'tmp/d' are the same file.
Error for the file "./tmp/c"
  cp: './tmp/c' and 'tmp/c' are the same file.
Error for the file "./tmp/a"
  cp: './tmp/a' and 'tmp/a' are the same file.
Error for the file "./tmp/b"
  cp: './tmp/b' and 'tmp/b' are the same file.