How do I save terminal output to a file?

Yes it is possible, just redirect the output (AKA stdout) to a file:

SomeCommand > SomeFile.txt  

Or if you want to append data:

SomeCommand >> SomeFile.txt

If you want stderr as well use this:

SomeCommand &> SomeFile.txt  

or this to append:

SomeCommand &>> SomeFile.txt  

if you want to have both stderr and output displayed on the console and in a file use this:

SomeCommand 2>&1 | tee SomeFile.txt

(If you want the output only, drop the 2 above)

To write the output of a command to a file, there are basically 10 commonly used ways.

Overview:

_{Please note that the n.e. in the syntax column means "not existing".
There is a way, but it's too complicated to fit into the column. You can find a helpful link in the List section about it.}

          || visible in terminal ||   visible in file   || existing
  Syntax  ||  StdOut  |  StdErr  ||  StdOut  |  StdErr  ||   file   
==========++==========+==========++==========+==========++===========
    >     ||    no    |   yes    ||   yes    |    no    || overwrite
    >>    ||    no    |   yes    ||   yes    |    no    ||  append
          ||          |          ||          |          ||
   2>     ||   yes    |    no    ||    no    |   yes    || overwrite
   2>>    ||   yes    |    no    ||    no    |   yes    ||  append
          ||          |          ||          |          ||
   &>     ||    no    |    no    ||   yes    |   yes    || overwrite
   &>>    ||    no    |    no    ||   yes    |   yes    ||  append
          ||          |          ||          |          ||
 | tee    ||   yes    |   yes    ||   yes    |    no    || overwrite
 | tee -a ||   yes    |   yes    ||   yes    |    no    ||  append
          ||          |          ||          |          ||
 n.e. (*) ||   yes    |   yes    ||    no    |   yes    || overwrite
 n.e. (*) ||   yes    |   yes    ||    no    |   yes    ||  append
          ||          |          ||          |          ||
|& tee    ||   yes    |   yes    ||   yes    |   yes    || overwrite
|& tee -a ||   yes    |   yes    ||   yes    |   yes    ||  append

List:

• command > output.txt

  The standard output stream will be redirected to the file only, it will not be visible in the terminal. If the file already exists, it gets overwritten.

• command >> output.txt

  The standard output stream will be redirected to the file only, it will not be visible in the terminal. If the file already exists, the new data will get appended to the end of the file.

• command 2> output.txt

  The standard error stream will be redirected to the file only, it will not be visible in the terminal. If the file already exists, it gets overwritten.

• command 2>> output.txt

  The standard error stream will be redirected to the file only, it will not be visible in the terminal. If the file already exists, the new data will get appended to the end of the file.

• command &> output.txt

  Both the standard output and standard error stream will be redirected to the file only, nothing will be visible in the terminal. If the file already exists, it gets overwritten.

• command &>> output.txt

  Both the standard output and standard error stream will be redirected to the file only, nothing will be visible in the terminal. If the file already exists, the new data will get appended to the end of the file..

• command | tee output.txt

  The standard output stream will be copied to the file, it will still be visible in the terminal. If the file already exists, it gets overwritten.

• command | tee -a output.txt

  The standard output stream will be copied to the file, it will still be visible in the terminal. If the file already exists, the new data will get appended to the end of the file.

• (*)

  Bash has no shorthand syntax that allows piping only StdErr to a second command, which would be needed here in combination with tee again to complete the table. If you really need something like that, please look at "How to pipe stderr, and not stdout?" on Stack Overflow for some ways how this can be done e.g. by swapping streams or using process substitution.

• command |& tee output.txt

  Both the standard output and standard error streams will be copied to the file while still being visible in the terminal. If the file already exists, it gets overwritten.

• command |& tee -a output.txt

  Both the standard output and standard error streams will be copied to the file while still being visible in the terminal. If the file already exists, the new data will get appended to the end of the file.

You can also use tee to send the output to a file:

command | tee ~/outputfile.txt

A slight modification will catch stderr as well:

command 2>&1 | tee ~/outputfile.txt

or slightly shorter and less complicated:

command |& tee ~/outputfile.txt

tee is useful if you want to be able to capture command output while also viewing it live.

You can redirect the command output to a file:

your_command >/path/to/file

To append the command output to a file instead of overwriting it, use:

your_command >>/path/to/file

An enhancement to consider -

Various scripts will inject color codes into the output which you may not want cluttering up your log file.

To fix this, you can use the program sed to strip out those codes. Example:

command 2>&1 | sed -r 's/'$(echo -e "\033")'\[[0-9]{1,2}(;([0-9]{1,2})?)?[mK]//g' | tee ~/outputfile.txt