Linux in bash_source[0] (go)

Transferred from: http://www.cnblogs.com/sunfie/p/5943979.html

The __function__ constant records the name of the current function in C + +. Sometimes it is useful to include this information in the log output. In bash, too, there is a constant funcname, but the difference is that it is an array, not a string, where the first element of the array is the name of the current function. Maybe it's a little hard to understand why funcname an array? Take a look at the example below and you'll see.

1 #!/bin/bash 2  3 function Test_func () 4 {5     echo "Current $FUNCNAME, \ $FUNCNAME = (${funcname[@]})" 6     ano Ther_func 7     echo "Current $FUNCNAME, \ $FUNCNAME = (${funcname[@]})" 8} 9 function Another_func () one {     Ech O "Current $FUNCNAME, \ $FUNCNAME = (${funcname[@]})"}14 echo "out of function, \ $FUNCNAME = (${funcname[@]}) "Test_func17 echo" out of function, \ $FUNCNAME = (${funcname[@]}) "

The result after execution is:

1 out of function, $FUNCNAME = () 2 current test_func, $FUNCNAME = = (test_func main) 3 current Another_func, $FUNCNAM E = (another_func test_func main) 4 current test_func, $FUNCNAME = (test_func main) 5 out of function, $FUNCNAME =&G T ()

So, to be more precise, funcname is an array, but it is maintained in bash as a stack-like form. Another useful constant similar to funcname is Bash_source, which is also an array, but its first element is the name of the current script. This is useful when source, because in the script that is source, $ A is the name of the parent script, not the script name of the source. And Bash_source can be handy.

1 # If the script is sourced by another script2 If [-N ' $BASH _source "-a" $BASH _source "! =" $ "]3 then4     do_something 5 Else # Otherwise, run directly in the shell6     do_other7 fi

Bash_source[0] Bash_source[0] is equivalent to Bash_source, obtaining the path and file name of the currently executing shell file.

Create a new script test.sh under the directory/home/sam/linux programming exercise/shell:

1 #!/bin/bash2 dir= "$ (CD" $ (dirname "${bash_source[0]}")/... /"&& pwd" 3 # dir=$ (CD "$ (dirname ${bash_source[0]})/... /"&& pwd) 4 # dir= ' CD $ (dirname ${bash_source[0]})/... /&& pwd ' 5 echo $DIR 6 echo "OK"

Execution requires a EXECUTE permission: chmod +x test.sh then execute ./test.sh instead ofsh ./test.sh

Tested above write correct: output

1/home/sam/linux Programming Exercise 2 OK

is actually a: 1. Get the full path of the currently executing shell file 2. Executes the dirname and enters the parent directory 3. Process for printing the current working directory

1 # echo "${bash_source[0"} "2 # echo" ${bash_source} "3 # echo" $ (dirname "${bash_source[0]}") "4 # dir=" $ (CD "$ (dirname ${BASH_SOURCE[0]}) "&& pwd" 5 # echo $DIR

Linux in bash_source[0] (go)