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Full Discussion: Cat/File Descriptor Question
Homework and Emergencies Homework & Coursework Questions Cat/File Descriptor Question Post 302993033 by ayz649 on Monday 6th of March 2017 02:14:43 AM
Old 03-06-2017
Cat/File Descriptor Question

For the command below, I need to understand what exactly the command does and provide an examples for which the output will be saved to file save2... From my understanding, if the file provides an error in the first half of the pipe, it'll save to save1 and will never give an error to save to save2. I'm just confused as to what exactly would cause it to save anything to save2.

2. Relevant commands, code, scripts, algorithms:
Code:
cat 2>save1 0<memo | sort 2>save2 1>letter

Any help with this or if anyone can provide a tutorial that goes into examples using a combination of cat, pipes and file descriptors I would really appreciate it!


4. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number:

Texas State University, San Marcos, TX, USA, Professor Quijun Gu, CS 4350

Moderator's Comments:
Mod Comment please use next time the full template, even if you believe to not enter in the orthodox form try your best, and dont forget to use for all code and data code tags , thanks

Last edited by vbe; 03-06-2017 at 03:59 AM..
 

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tee(1)							      General Commands Manual							    tee(1)

NAME
tee - Displays the output of a program and copies it into a file SYNOPSIS
tee [-ai] file... STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: tee: XCU5.0 Refer to the standards(5) reference page for more information about industry standards and associated tags. OPTIONS
Adds the output to the end of file instead of writing over it. Ignores the SIGINT signal. OPERANDS
Standard input is stored into, or appended to, the file specified. [Tru64 UNIX] The tee command can accept up to 20 file arguments. DESCRIPTION
The tee command reads standard input and writes to both standard output, and each specified file. The tee command is useful when you wish to view program output as it is displayed, and also want to save it in a file. The tee command does not buffer output, so you may wish to pipe the output of tee to more if more than one full screen of data is anticipated. NOTES
If a write to any file fails, the exit status of tee will be non-zero. Writes to all other specified files may be successful, and opera- tion will continue until standard input is exhausted. EXIT STATUS
The following exit values are returned: Successful completion. An error occurred. EXAMPLES
To view and save the output from a command at the same time, enter: lint program.c | tee program.lint This displays the standard output of the command lint program.c at the terminal, and at the same time saves a copy of it in the file program.lint. If program.lint already exists, it is deleted and replaced. To display and append to a file, enter: lint program.c | tee -a program.lint This displays the standard output of lint program.c at the terminal and at the same time appends a copy of it to the end of pro- gram.lint. If the file program.lint does not exist, it is created. ENVIRONMENT VARIABLES
The following environment variables affect the execution of tee: Provides a default value for the internationalization variables that are unset or null. If LANG is unset or null, the corresponding value from the default locale is used. If any of the internationalization vari- ables contain an invalid setting, the utility behaves as if none of the variables had been defined. If set to a non-empty string value, overrides the values of all the other internationalization variables. Determines the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multibyte characters in arguments). Determines the locale for the for- mat and contents of diagnostic messages written to standard error. Determines the location of message catalogues for the processing of LC_MESSAGES. SEE ALSO
Commands: cat(1), echo(1), script(1) Standards: standards(5) tee(1)
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