[Root @ localhost ~] # Echo $ {mail}
/Var/spool/mail/root
[Root @ localhost ~] # Echo $ {mail ###/*/} # pre-Greedy match Deletion
Root
[Root @ localhost ~] # Echo $ {mail #/*/} # pre-match Deletion
Spool/mail/root
[Root @ localhost ~] # Echo $ {mail %/*} # match and delete
/Var/spool/mail
[Root @ localhost ~] # Echo $ {mail %/*} # delete a greedy match
[Root @ localhost ~] # Echo $ {mail // oo/AA} # global replacement
/Var/spaal/mail/raat
[Root @ localhost ~] # Echo $ {mail/OO/AA} # Replace only the first one
/Var/spaal/mail/root
[Root @ localhost ~] # Unset A; var =$ {a-B}; echo $ A, $ var # Var = (a = NULL )? A: B
, B
[Root @ localhost ~] # A = 'foo'; var =$ {a-B}; echo $ A, $ VaR
Foo, foo
[Root @ localhost ~] # Unset A; var =$ {a = B}; echo $ A, $ var # Var = A = (a = NULL )? A: B
B, B
[Root @ localhost ~] # A = 'foo'; var =$ {a = B}; echo $ A, $ VaR
Foo, foo
Variable setting method |
STR not set |
STR is a NULL Character |
STR has been set to a non-empty character |
VaR =$ {str-expr} |
Var = expr |
Var = |
Var = $ Str |
VaR =$ {STR:-expr} |
Var = expr |
Var = expr |
Var = $ Str |
VaR =$ {STR + expr} |
Var = expr |
Var = expr |
Var = expr |
VaR =$ {STR: + expr} |
Var = expr |
Var = |
Var = expr |
VaR =$ {STR = expr} |
Var = expr STR = expr |
STR unchanged Var = |
STR unchanged Var = $ Str |
VaR =$ {STR: = expr} |
Var = expr STR = expr |
Var = expr STR = expr |
STR unchanged Var = $ Str |
VaR =$ {Str? Expr} |
Expr output to stderr |
Var = |
Var = $ Str |
VaR =$ {STR :? Expr} |
Expr output to stderr |
Expr output to stderr |
Var = $ Str |