: :
: : 3개의 차이점을 알고 싶습니다.
: :
: : .bash_profile을 편집하고 . .bash_profile을 하라고
: :
: : 하는데 왜 해야하는지요?
: :
: : /etc/profile을 편집하고 source /etc/profile을 하라고 하는데
: :
: : 왜 해야하는지요?
: :
: : 그리고 어떤 file을 편집하고 sync를 하라고 하는데 왜 인지요?
: :
: : 이 3개의 차이점을 가르쳐 주세요?ㅑ
:   
: answer: 'sync' writes any data brffered in memory out to disk.
:         This can include (but is not limited to) modified superblocks,
:          modified inodes, and delayed reads and writes. The must be
:          implemented by the kerner;
:          The 'sync' program does nothing but exercise the 'syne' system call.
:
:          The kernel keeps date in memory to avoid doing (relatively slow)
:          disk reads and writes. This improves performance, but if the computer
:          crashes, doata may be lost or the filesystem corrupted as a result.
:          'sync' ensures everything in memory is written to disk.
:
:        'source'