Golang (go language) standard Library analysis OS (8)

This is a creation in Article, where the information may have evolved or changed.

Golang Standard Library

Today we continue the OS package, not much to say a word is Golang OS package

(1) Type FileInfo inside two functions stat and lstat I'm not going to say much, using the same method. We also introduced
[PHP]
Import (
"FMT"
"OS"
)

Func Main () {
It's about the stat.
F, _: = OS. Lstat ("1.go")
Fmt. Println (f)//&{1.go {2883792444 30345044} {2884358853 30345044} {3464863792 30345293} 0} {0 0} D:\test\1.go 0 0 0}
}

Type FileMode
Func (M FileMode) isdir () bool
Func (M FileMode) isregular () bool
Func (M FileMode) Perm () FileMode
Func (M FileMode) string () string

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(2) This filemode is mainly used for judging and exporting permissions, this is not much to say, so I'll just give you a test of the code

[PHP]
Import (
"FMT"
"OS"
"Reflect"
)

Func Main () {
F, _: = OS. Stat ("1.go")
Fi: = F.mode ()
Fmt. Println (reflect. TypeOf (FI))//os. FileMode
Fmt. Println (FI. Isdir ())//false determine if it is a directory
Fmt. Println (FI. Isregular ())//true determine if it is a regular file
Fmt. Println (FI. Perm ())//-rw-rw-rw-returns the Unix plain
Fmt. Println (FI. String ())//-rw-rw-rw-returns a string form of the file pattern
}

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(3) func (e *linkerror) Error () string This function is to get the Linkerror string form, first we look at the structure

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Type Linkerror struct {
Op string
Old string
New string
ERR Error
}

Import (
"Errors"
"FMT"
"OS"
)

Func Main () {
Linkerror: = &os. linkerror{
Op: "Widuu",
Old: ' Old ',
NEW: "New Error",
Err:errors. New ("Error Test"),
}
Fmt. Println (Linkerror. Error ())//widuu old New Error:error test
}

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(4) func (e *patherror) Error () string This function is to get the Patherror string form, and then we look at its structure

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Type Patherror struct {
Op string
Path string
ERR Error
}
Import (
"Errors"
"FMT"
"OS"
)

Func Main () {
Patherr: = &os. patherror{
Op: "dir",
Path: "Widuu",
Err:errors. New ("No Path"),
}
Fmt. Println (Patherr. Error ())//dir Widuu:no Path
}

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(5) Type process we are talking about the method under this structure

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Type Process struct {
Pid int
}
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[1] Findprocess () function prototype func findprocess (PID int) (P *process, err Error) The PID of the input process returns the pointer structure of the process and the error information

[PHP]
Import (
"FMT"
"OS"
)

Func Main () {
P, _: = OS. Findprocess (6816)//Now cmd under my native windows
Fmt. PRINTLN (p)//&{6816 236 0}
}
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[2]os. StartProcess () function prototype func startprocess (name string, argv []string, attr *procattr) (*process, error) function is a new process, You must enter a name and parameter to specify the environment, this is a low-level interface, when we say os/exec there are more advanced interfaces, the return is the structure of the process and Patherror

[PHP]
Import (
"FMT"
"OS"
)

Func Main () {
attr: = &os. procattr{
Files: []*os. File{os. Stdin, OS. Stdout, OS. Stderr},//note here ha
}
P, err: = OS. StartProcess (' C:\windows\system32\notepad. EXE ', []string{' C:\windows\system32\notepad. EXE ', ' d:/1.txt '}, attr)//windows open folder under 1.txt
If err! = Nil {
Fmt. Println (Err. Error ())
}
Fmt. PRINTLN (p)//&{5488 240 0}
}

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[3]func (P *process) Kill () error A look we know is the kill process, we tested

[PHP]
Import (
"FMT"
"OS"
)

Func Main () {
P, _: = OS. Findprocess (7588)//Now cmd under my native windows
Fmt. PRINTLN (p)//&{7588 224 0}
ERR: = P.kill ()
If err! = Nil {
Fmt. PRINTLN (ERR)
}
Fmt. PRINTLN ("Kill process")
}

Very depressed thing is ~ ~ ~ I am using this process godoc-http:=8080 still stay again * * *
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[4]func (P *process) release () error This is the resource for the release process. and take the experiment.

[PHP]
Import (
"FMT"
"OS"
)

Func Main () {
attr: = &os. procattr{
Files: []*os. File{os. Stdin, OS. Stdout, OS. Stderr},
}
P, err: = OS. StartProcess (' C:\windows\system32\notepad. EXE ', []string{' C:\windows\system32\notepad. EXE ', ' d:/1.txt '}, attr)//windows open folder under 1.txt
If err! = Nil {
Fmt. Println (Err. Error ())//&{7704 244 0}
}
Fmt. PRINTLN (P)
If err: = P.release (); Err! = Nil {
Fmt. Printf ("Error:%v\n", err)
}
}

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[5]func (P *process) Signal (sig Signal) Error This is for sending a signal to a process.

[PHP]
Import (
"FMT"
"OS"
)

Func Main () {
attr: = &os. procattr{
Files: []*os. File{os. Stdin, OS. Stdout, OS. Stderr},
}
P, _: = OS. StartProcess (' C:\windows\system32\notepad. EXE ', []string{' C:\windows\system32\notepad. EXE ', ' d:/1.txt '}, attr)
Fmt. PRINTLN (P)
If err: = p.signal (OS. Kill); Err! = Nil {//Send a signal to the system to kill him so our familiar notepad won't come out.
Fmt. PRINTLN (ERR)
}
}

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[6]func (P *process) Wait () (*processstate, error) as soon as you see, this function is waiting for the function of the process to complete, and then return the process struct body pointer to the

[PHP]
Import (
"FMT"
"OS"
)

Func Main () {
attr: = &os. procattr{
Files: []*os. File{os. Stdin, OS. Stdout, OS. Stderr},
}
P, _: = OS. StartProcess (' C:\windows\system32\notepad. EXE ', []string{' C:\windows\system32\notepad. EXE ', ' d:/1.txt '}, attr)
PW, _: = P.wait ()
Fmt. Println (PW)//exit status 0
}

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(6) We tell the structure of type processstate struct {} and the method inside

[1]func (P *processstate) Exited () bool to see if the process exited

[PHP]
Import (
"FMT"
"OS"
)

Func Main () {
attr: = &os. procattr{
Files: []*os. File{os. Stdin, OS. Stdout, OS. Stderr},
}
P, _: = OS. StartProcess (' C:\windows\system32\notepad. EXE ', []string{' C:\windows\system32\notepad. EXE ', ' d:/1.txt '}, attr)
Fmt. PRINTLN (p)//&{7764 252 0}
PW, _: = P.wait ()
Fmt. Println (PW. Exited ())//When I close Notepad, the process ends, so even true
}
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[2] func (p *ProcessState) Pid () int very simple to return the pid of the process, the rest I will not say one by one, then directly explain and then do the experiment



[3] func (p *ProcessState) String() string This function is mainly a string to get the state of the process.

[4]func (p *ProcessState) Success() bool This function reports whether to exit

[5] func (p *ProcessState) Sys () interface{} This function is mainly to get the exit information of the process

[6] func (p *ProcessState) SysUsage () interface{} This function is mainly to obtain process resource usage

[7] func (p *ProcessState) SystemTime() time.Duration This function is mainly used to obtain the system cpu usage time of the process.



[8] func (p *ProcessState) UserTime() time.Duration This function is mainly used to get the user cpu usage time of the process.

[PHP]
Import (
"FMT"
"OS"
)

Func Main () {
attr: = &os. procattr{
Files: []*os. File{os. Stdin, OS. Stdout, OS. Stderr},
}
P, _: = OS. StartProcess (' C:\windows\system32\notepad. EXE ', []string{' C:\windows\system32\notepad. EXE ', ' d:/1.txt '}, attr)
Fmt. PRINTLN (p)//&{44 252 0}
PW, _: = P.wait ()
Fmt. Println (PW. Pid ())//44
Fmt. Println (PW. String ())//exit status 0
Fmt. Println (PW. Success ())//true
Fmt. Println (PW. Sys ())//{0}
Fmt. Println (PW. Sysusage ())//&{{1728533532 30345488} {1745163891 30345488} {1562500 0} {1562500 0}}
Fmt. Println (PW. SystemTime ())//156.25ms
Fmt. Println (PW. Usertime ())//156.25ms
}

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(7) func (e *syscallerror) Error () string This function is mainly to get syscallerror string form

[PHP]
Type Syscallerror struct {
Syscall string
ERR Error
}
Import (
"Errors"
"FMT"
"OS"
)

Func Main () {
ERR: = &os. syscallerror{
Syscall: "Widuu",
Err:errors. New ("Syscall error"),
}
Fmt. Println (Err. Error ())//widuu:syscall error
}
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Today's OS package is over, tomorrow we continue to talk about the OS sub-package, then thank you for your attention to my blog [Micro Network | Network Technology Support Center] (http://www.widuu.com) http://www.widuu.com***

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