我想使用tail作为stdin从文本文件中发送程序最新的行。
首先，我向程序回显一些每次都相同的输入，然后从输入文件发送尾输入，该输入文件应首先通过sed处理。以下是我期望工作的命令行。但是当程序运行时，它只接收回声输入，而不是尾部输入。
(echo "new" && tail -f ~/inputfile 2> /dev/null | sed -n -r 'some regex' && cat) | ./program
但是，以下工作完全符合预期，将所有内容打印到终端：
echo "new" && tail -f ~/inputfile 2> /dev/null | sed -n -r 'some regex' && cat
所以我尝试了另一种类型的输出，并且在发布回声文本的同时，尾部文本没有出现在任何地方：
(echo "new" && tail -f ~/inputfile 2> /dev/null | sed -n -r 'some regex') | tee out.txt
这让我觉得这是一个缓冲问题，但我尝试了unbuffer程序和所有其他建议（https://superuser.com/questions/59497/writing-tail-f-output-to-another-file）没有结果。尾部输出在哪里，如何按预期进入我的程序？
答案 0 :(得分：1)
当我使用以下命令为sed命令添加前缀时，解决了缓冲问题：
stdbuf -i0 -o0 -e0
使用非缓冲更为可取，这对我来说根本不起作用。 Dave M建议使用sed相对较新的-u似乎也可以解决问题。
答案 1 :(得分：1)
您可能会感到困惑的一件事 - |（管道）的优先级高于&&（连续执行）。所以当你说
(echo "new" && tail -f ~/inputfile 2> /dev/null | sed -n -r 'some regex' && cat) | ./program
相当于
(echo "new" && (tail -f ~/inputfile 2> /dev/null | sed -n -r 'some regex') && cat) | ./program
所以cat并没有真正做任何事情，sed输出可能有点缓冲。您可以尝试使用-u sed选项来使其使用无缓冲输出：
(echo "new" && (tail -f ~/inputfile 2> /dev/null | sed -n -u -r 'some regex')) | ./program
我认为当输出是终端时，某些版本的sed默认为-u，而不是当它是管道时，因此这可能是您所看到的差异的来源。
答案 2 :(得分：0)
您可以在 //PHOTO ONE UPLOAD TAKE AND SELECT
- (IBAction)selectPhoto:(id)sender {
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
selectedImageView = self.imageView; // Add this
[self presentViewController:picker animated:YES completion:NULL];
}
- (IBAction)takePhoto:(id)sender {
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
selectedImageView = self.imageView; // Add this
[self presentViewController:picker animated:YES completion:NULL];
}
- (IBAction)takePhotoTwo:(id)sender {
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
selectedImageView = self.imageTwo; // Add this
[self presentViewController:picker animated:YES completion:NULL];
}
- (IBAction)selectPhotoTwo:(id)sender {
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
selectedImageView = self.imageTwo; // Add this
[self presentViewController:picker animated:YES completion:NULL];
}
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
UIImage *image = info[UIImagePickerControllerEditedImage];
selectedImageView.image = image;
[picker dismissViewControllerAnimated:YES completion:NULL];
}
- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
[picker dismissViewControllerAnimated:YES completion:NULL];
}
- (IBAction)saveButton:(id)sender {
//FIRST IMAGE DATA
NSData *imgData = UIImageJPEGRepresentation(self.imageView.image, 0.5);
NSMutableDictionary *file = [[NSMutableDictionary alloc] init];
NSString *base64Image = [imgData base64EncodedString];
[file setObject:base64Image forKey:@"file"];
NSString *timestamp = [NSString stringWithFormat:@"%d", (int)[[NSDate date] timeIntervalSince1970]];
NSString *imageTitle = _itemName.text;
NSString *filePath = [NSString stringWithFormat:@"%@%@.jpg",@"public://stored/", imageTitle];
NSString *fileName = [NSString stringWithFormat:@"%@.jpg", imageTitle];
[file setObject:filePath forKey:@"filepath"];
[file setObject:fileName forKey:@"filename"];
[file setObject:timestamp forKey:@"timestamp"];
NSString *fileSize = [NSString stringWithFormat:@"%lu", (unsigned long)[imgData length]];
[file setObject:fileSize forKey:@"filesize"];
//SECOND IMAGE DATA
NSData *secondimgData = UIImageJPEGRepresentation(self.imageTwo.image, 0.5);
NSMutableDictionary *secondfile = [[NSMutableDictionary alloc] init];
NSString *secondbase64Image = [secondimgData base64EncodedString];
[file setObject:secondbase64Image forKey:@"file"];
NSString *secondtimestamp = [NSString stringWithFormat:@"%d", (int)[[NSDate date] timeIntervalSince1970]];
NSString *secondimageTitle = secondtimestamp;
NSString *secondfilePath = [NSString stringWithFormat:@"%@%@.jpg",@"public://stored/", secondimageTitle];
NSString *secondfileName = [NSString stringWithFormat:@"%@.jpg", secondimageTitle];
[secondfile setObject:secondfilePath forKey:@"filepath"];
[secondfile setObject:secondfileName forKey:@"filename"];
[secondfile setObject:secondtimestamp forKey:@"timestamp"];
NSString *secondfileSize = [NSString stringWithFormat:@"%lu", (unsigned long)[secondimgData length]];
[secondfile setObject:secondfileSize forKey:@"filesize"];
[DIOSFile fileSave:file success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(@"File uploaded!");
//FIRST IMAGE FILE
[file setObject:[responseObject objectForKey:@"fid"] forKey:@"fid"];
[file removeObjectForKey:@"file"];
fid = [responseObject objectForKey:@"fid"];
NSLog(@"%@",responseObject);
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
[dict setObject: [NSString stringWithFormat:@"%@", fid] forKey:@"fid"];
NSLog(@"%@", fid);
NSDictionary *fidLangDict = [NSDictionary dictionaryWithObject:[NSArray arrayWithObject:dict] forKey:@"und"];
[nodeData setObject:fidLangDict forKey:@"field_photo"];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(@"Node did not save!");
}];
[DIOSFile fileSave:file success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(@"File uploaded!");
//SECOND IMAGE FILE
[secondfile setObject:[responseObject objectForKey:@"fid"] forKey:@"fid"];
[secondfile removeObjectForKey:@"file"];
fid = [responseObject objectForKey:@"fid"];
NSLog(@"%@",responseObject);
NSMutableDictionary *secondDict = [NSMutableDictionary dictionary];
[secondDict setObject: [NSString stringWithFormat:@"%@", fid] forKey:@"fid"];
NSLog(@"%@", fid);
NSDictionary *secondfidLangDict = [NSDictionary dictionaryWithObject:[NSArray arrayWithObject:secondDict] forKey:@"und"];
[nodeData setObject:secondfidLangDict forKey:@"phototwo"];
[DIOSNode nodeSave:nodeData success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(@"Node saved!");
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main_iPad" bundle:nil];
ipadaccountViewController *AccountViewController = (ipadaccountViewController *)[storyboard instantiateViewControllerWithIdentifier:@"MyAccount"];
[self.navigationController popViewControllerAnimated:TRUE];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(@"Node did not save!");
}];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(@"Node did not save!");
}];
中使用<field_photo>
<und is_array="true">
<item>
<fid>265</fid>
<uid>5</uid>
<filename>phone.jpg</filename>
<uri>public://stored/phone_1.jpg</uri>
<filemime>image/jpeg</filemime>
<filesize>161858</filesize>
<status>1</status>
<timestamp>1460264800</timestamp>
<rdf_mapping/>
<alt/>
<title/>
<width>1536</width>
<height>1536</height>
</item>
</und>
</field_photo>
<phototwo>
<und is_array="true">
<item>
<fid>266</fid>
<uid>5</uid>
<filename>phone.jpg</filename>
<uri>public://stored/phone_2.jpg</uri>
<filemime>image/jpeg</filemime>
<filesize>161858</filesize>
<status>1</status>
<timestamp>1460264800</timestamp>
<rdf_mapping/>
<alt/>
<title/>
<width>1536</width>
<height>1536</height>
</item>
</und>
</phototwo>
命令（有关详细信息，请参阅联机帮助页中的命令列表），以便在开头插入：
i