Clean way to print command used to run script (stdin), stdout and stderr into file

Question

I was attempting to run a script in bash: cc.sh

To run the bash script:

../cc.sh ../seq/ seqf

where ../seq/ and seqf are both arguments required.

I wanted to save the command I used to run the script (the command above), together with the output/result from the script into a log file.

I managed to print the output into a log file with tee command.

../cc.sh ../seq/ seqf 2<&1 | tee -a cc.log

cat cc.log:

"here is where the output shown"

While for the command itself, the closest I got is the script command. However, it seemed to save the command I used to run in a binary file.

Is there other better way to print the command other than script? Or better, print the command used to run the script file, together with the output/result into a log file?

Expected output for the log file:

COMMAND: ../cc.sh ../seq/ seqf
"here is where the output shown"

Answer 1

The simplest way is to modify your script to make it print its name and argument list to standard output. For example, if the file of your script contains echo $0 $@ as the first line, it will print the info you need (assuming it uses sh and is launched from bash):

#!/bin/sh
echo "$0 $@"

and then you can just redirect stdout to file, tee or whatever you want.

Answer 2

Use an array to store the command and its arguments. Print the command (the array) to the output file, then execute the command. Pipe all output to tee to append it to the cc.log file:

mycommand=( ../cc.sh ../seq/ seqf )

{
    printf 'COMMAND: %s\n' "${mycommand[*]}"
    "${mycommand[@]}"
} | tee -a cc.log

This creates the array mycommand and sets its elements to the command and its arguments. The command is then printed, prefixed by the string COMMAND: . The expansion "${mycommand[*]}" will be a single string made up of the elements of the array delimited by the first character of $IFS (usually a space).

The expansion "${mycommand[@]}" will be a list of individual quoted strings, i.e. the command and its individually quoted arguments. Using the expansion like this would cause the command to be correctly invoked.

The output from both printf and the command is redirected together to tee, one after the other, since they are part of the same compound command ({...;}).

Or, using the list of positional parameters instead of a named array,

set -- ../cc.sh ../seq/ seqf

{
    printf 'COMMAND: %s\n' "$*"
    "$@"
} | tee -a cc.log

Note that this would work for any command, whether a shell script or a compiled binary executable.