bash：如何给function传参数
给shell里的函数（function）传递参数有2种方式：
第一种方式：
在function里直接通过$1,$2,etc.来获取参数：
例：
建立一个文件“file.txt”在shell里创建一个函数并调用：
file.txt:
chen china engineer lee china leader lynn china programmer
funcTest.sh:
myfunc () { echo "params length: $#" #“$#”会显示传给该函数的参数个数 echo "all params : $@" #“$@”会显示所有传给函数的参数 echo "/$1: $1" echo "/$2: $2" echo "/$3: $3" echo "/$4: $4" echo "/$5: $5" echo "/$6: $6" echo "/$7: $7" echo "/$8: $8" echo "/$9: $9" echo "/$0: $0" } myfunc `grep china file.txt`
该shell的执行结果：
-bash-3.00$ ./funcTest.sh params length: 9 all params : chen china engineer lee china leader lynn china programmer $1: chen $2: china $3: engineer $4: lee $5: china $6: leader $7: lynn $8: china $9: programmer $0: ./funcTest.sh
从上面的结果可以看出通过这种传递方式grep结果里的换行已经被无视了，本来应该是3行*3个参数，直接被当做9个参数了。
另外，$0在这里指的是shell脚本名。
第二种方式：
使用awk：
例：
myfunc2 () { awk '{ printf("$1:%s/n", $1) printf("$2:%s/n", $2) printf("$3:%s/n", $3) printf("$0:%s/n", $0) printf("-----------/n") }' } grep china file.txt|myfunc2
执行结果：
$1:chen $2:china $3:engineer $0:chen china engineer ----------- $1:lee $2:china $3:leader $0:lee china leader ----------- $1:lynn $2:china $3:programmer $0:lynn china programmer
可以看到，awk可以分3次进行处理，相当于调用了3遍myfunc2.
此外还有一点，$0在这里指的是本次调用的所有参数。
注意点：
第一种方式不支持管道传参，使用“grep china file.txt|myfunc”将得不到你想要的结果。
相反第二种方式（awk方式）只支持管道传参，而不支持“myfunc2 `grep china file.txt`”的调用方式。
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提示：
Built-in Shell Variables：
$# : Number of command-line arguments.
$- : Options currently in effect (supplied on command line or to set). The shell sets some options automatically.
$? : Exit value of last executed command.
$$ : Process number of the shell.
$! : Process number of last background command.
$0 : First word; that is, the command name. This will have the full
pathname if it was found via a PATH search.
$n : Individual arguments on command line (positional parameters).
The Bourne shell allows only nine parameters to be referenced
directly (n = 1–9); Bash allows n to be greater than 9
if specified as ${n}.
$*, $@ : All arguments on command line ($1 $2 …).
"$*" : All arguments on command line as one string ("$1 $2…"). The
values are separated by the first character in $IFS.
"$@" : All arguments on command line, individually quoted ("$1" "$2" …).
$_ : Temporary variable; initialized to pathname
of script or program being executed.
Later, stores the last argument of previous
command. Also stores name of matching
MAIL file during mail checks.