Print on Terminal and into File Simultaneously

Print on terminal and into file simultaneously?

Pipe your output to the tee command.

Example:

[me@home]$ echo hello | tee out.txt
hello
[me@home]$ cat out.txt 
hello

Note that the stdout of echo is printed out as well as written to the file specified by thr tee command.

How to show output on terminal and save to a file at the same time in C?

Ways to solve printing to the terminal and saving output to file

• Using printf(), or fprintf(stdin, ""); to stdin, statement after fprintf();
• Using system("cat output.log");(works in linux) after writing to file.
• Using function which will print the file after writing like

#include <stdio.h>
void printFile(FILE *fp) {
  char line[2048];
  while (fscanf(fp, "%[^\n]s", line) == 1) {
    printf("%s\n", line);
    fgetc(fp); // OR fseek(fp, 1, 1); To throw away the new line in the input
               // buffer
  }
}
int main() {
  FILE *fp;
  fp = fopen("a.txt", "r");
  if (fp == NULL) {
    printf("Error opening the file\n");
    return 1;
  }
  printFile(fp);
  return 0;
}

• Using linux shell
  
  ./a.out | tee output.log
  and use normal printf() statement inside your C code.

linux terminal: how to copy output to a file and print at terminal simultaneously?

Use tee command to achieve the same.

command | tee output.txt

Displaying stdout on screen and a file simultaneously

I can't say why tail lags, but you can use tee:

Redirect output to multiple files, copies standard input to standard output and also to any files given as arguments. This is useful when you want not only to send some data down a pipe, but also to save a copy.

Example: <command> | tee <outputFile>

Direct output to standard output and an output file simultaneously

Use tee:

./executable 2>&1 | tee outputfile

tee outputs in chunks and there may be some delay before you see any output. If you want closer to real-time output, you could redirect to a file as you are now, and monitor it with tail -f in a different shell:

./executable 2>&1 > outputfile

tail -f outputfile

Is is possible to log everything that is printed to the terminal into a text file in C?

You can do: ./executable > outputfile 2>&1 or ./executable &> outputfile

This will enable you to redirect both the standard output and the standard output to the outputfile.

How to redirect output to a file and stdout

The command you want is named tee:

foo | tee output.file

For example, if you only care about stdout:

ls -a | tee output.file

If you want to include stderr, do:

program [arguments...] 2>&1 | tee outfile

2>&1 redirects channel 2 (stderr/standard error) into channel 1 (stdout/standard output), such that both is written as stdout. It is also directed to the given output file as of the tee command.

Furthermore, if you want to append to the log file, use tee -a as:

program [arguments...] 2>&1 | tee -a outfile

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