Em Java, como definir a permissão de arquivo em um arquivo usando PosixFilePermission? Entendendo o comando chmod
Publicados: 2021-06-28
Como definir a permissão de arquivo em Java? Aqui está um exemplo simples de configuração de permissão de arquivo em qualquer arquivo fornecido.
Se você faz parte da unidade de negócios de Operações de qualquer empresa, é muito importante automatizar o fluxo de trabalho de implantação, fluxo de trabalho de análise e assim por diante.
Às vezes, seu programa Java sai com exceção se você tentar executar algum comando e, de alguma forma, para um determinado arquivo, você não tem permissão para executar o arquivo de script.
No nosso caso, é o arquivo Crunchify.sh .
Aqui está um programa Java simples que mostra como configurar a permissão de arquivo em qualquer arquivo.
CrunchifySetFilePermission.java
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package crunchify . com . java . tutorials ; import java . io . IOException ; import java . nio . file . Files ; import java . nio . file . Paths ; import java . nio . file . attribute . PosixFilePermission ; import java . util . HashSet ; import java . util . Set ; import java . io . File ; /** * @author Crunchify.com * In Java how to Set File Permission on a File using PosixFilePermission? Understanding chmod command. */ public class CrunchifySetFilePermission { public static void main ( String [ ] args ) { // File class: An abstract representation of file and directory pathnames. // User interfaces and operating systems use system-dependent pathname strings to name files and directories. // This class presents an abstract, system-independent view of hierarchical pathnames. File file = new File ( "/Users/app/Download/crunchify.txt" ) ; /* -------------------------- Set Permission: 455 ----------------------- */ // A convenience method to set the owner's execute permission for this abstract pathname. // On some platforms it may be possible to start the Java virtual machine with special privileges that allow it to execute files that are not marked executable. file . setExecutable ( false ) ; // public boolean setExecutable(boolean executable) // A convenience method to set the owner's read permission for this abstract pathname. // On some platforms it may be possible to start the Java virtual machine with special privileges that allow it to read files that are marked as unreadable. file . setReadable ( false ) ; // A convenience method to set the owner's write permission for this abstract pathname. // On some platforms it may be possible to start the Java virtual machine with special privileges that allow it to modify files that disallow write operations. file . setWritable ( true ) ; /* -------------------------- Set Permission: 777 ----------------------- */ // public boolean setExecutable(boolean executable, boolean ownerOnly) file . setExecutable ( true , false ) ; file . setReadable ( true , false ) ; file . setWritable ( true , false ) ; // using PosixFilePermission to set file permissions 777. PosixFilePermission - defines the bits for use with the permissions attribute. // The PosixFilePermissions class defines methods for manipulating set of permissions // HashSet: Constructs a new, empty set; the backing HashMap instance has default initial capacity (16) and load factor (0.75). Set < PosixFilePermission > crunchifyPermissions = new HashSet < PosixFilePermission > ( ) ; // add() Adds the specified element to this set if it is not already present (optional operation). // More formally, adds the specified element e to this set if the set contains no element e2 such that Objects.equals(e, e2). // If this set already contains the element, the call leaves the set unchanged and returns false. // In combination with the restriction on constructors, this ensures that sets never contain duplicate elements. /* -------------------------- OWNER Permissions ----------------------- */ // Read permission, owner. crunchifyPermissions . add ( PosixFilePermission . OWNER_READ ) ; // Write permission, owner. crunchifyPermissions . add ( PosixFilePermission . OWNER_WRITE ) ; // Execute/search permission, owner. crunchifyPermissions . add ( PosixFilePermission . OWNER_EXECUTE ) ; /* -------------------------- GROUP Permissions ----------------------- */ // PosixFilePermission: Defines the bits for use with the permissions attribute. // The PosixFilePermissions class defines methods for manipulating set of permissions. // Read permission, group. crunchifyPermissions . add ( PosixFilePermission . GROUP_READ ) ; // Write permission, group. crunchifyPermissions . add ( PosixFilePermission . GROUP_WRITE ) ; // Execute/search permission, group. crunchifyPermissions . add ( PosixFilePermission . GROUP_EXECUTE ) ; /* -------------------------- OTHERS Permissions ----------------------- */ // Read permission, others. crunchifyPermissions . add ( PosixFilePermission . OTHERS_READ ) ; // Write permission, others. crunchifyPermissions . add ( PosixFilePermission . OTHERS_WRITE ) ; // Execute/search permission, others. crunchifyPermissions . add ( PosixFilePermission . OTHERS_EXECUTE ) ; try { // Sets a file's POSIX permissions. // The path parameter is associated with a FileSystem that supports the PosixFileAttributeView. This attribute view provides access to file // attributes commonly associated with files on file systems used by operating systems that implement the Portable Operating System Interface (POSIX) family of standards. Files . setPosixFilePermissions ( Paths . get ( "/Users/app/Download/crunchify.sh" ) , crunchifyPermissions ) ; // Paths: This class consists exclusively of static methods that return a Path by converting a path string or URI. System . out . println ( "File permission set successfully..." ) ; } catch ( IOException e ) { // Signals that an I/O exception of some sort has occurred. This class is the general class of exceptions produced by failed or interrupted I/O operations. e . printStackTrace ( ) ; } } } |
Basta executar acima do Programa Java e você deverá ver a permissão do arquivo Crunchify.sh como abaixo.
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- rwxrwxrwx 1 crunchify crunchify 65 Jun 23 14 : 42 crunchify . sh |
Se você remover ou comentar abaixo de 3 arquivos, a permissão será alterada conforme abaixo:
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// crunchifyPermissions.add(PosixFilePermission.OTHERS_READ); // crunchifyPermissions.add(PosixFilePermission.OTHERS_WRITE); // crunchifyPermissions.add(PosixFilePermission.OTHERS_EXECUTE); |
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- rwxrwx --- 1 crunchify crunchify 65 Jun 23 14 : 42 crunchify . sh |
Vamos entender as permissões de arquivo do Linux:
Aqui está uma lista de todas as permissões:
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Deixe-nos saber se você enfrentar qualquer problema ao executar o programa acima.
