Running docker commands with bash variables

Question

For some reason, running docker commands from bash scripts doesn't work if you add regular variables, example:

c=$(date +"%x")
targets="www.example.com"

docker build -t amass https://github.com/OWASP/Amass.git
docker run amass --passive -d $targets > $c.txt

The error is as follows:

./main.sh: 13: ./main.sh: cannot create 12/29/2018.txt: Directory nonexistent

Running same commands from a terminal operate directly. How can I fix this?

Can you show main.sh ? Do you have a directory amass_out_12/29 in your docker? — Walter A
– Walter A, Commented Dec 29, 2018 at 13:55
Updating main post to full script. I don't have that directory in my docker, this should stdout to my host - or should it? (also - its a file not a directoryooooooo! I just realized the numbers of the date.time now may be interpreted as folders!). — tatoe
– tatoe, Commented Dec 29, 2018 at 14:01
Yes, change the date format, e.g. c=$(date +"%d-%m-%y") otherwise it means subdirectories. Also, as @Cyrus highlighted in the first comment, it's always good to write the shebang as first line of your scripts, so you are sure about the script intepreter to use ( #!/bin/bash that differs from #!/bin/sh ) — gile
– gile, Commented Dec 29, 2018 at 14:12

Bsquare ℬℬ · Accepted Answer · 2018-12-30 16:31:02Z

1

In your situation, it is too dangerous to use the %x option of date, which stands for:

%x locale's date representation (e.g., 12/31/99)

You wouldn't control anything, and may have various behaviour between your testing computer, and the docker, if the locale is different.

Anyway, using date format with slash '/', which are going to be interpreted as directory separator will lead to issue.

For both reasons, you should define the format of your date.

For instance:

#!/bin/bash

c=$(date +'%Y-%m-%d-%H-%M-%S')
targets="www.example.com"

docker build -t amass https://github.com/OWASP/Amass.git
docker run amass --passive -d $targets > $c.txt

You should add as many information (hour, minute, second ...) in your date as you think you may run your script; otherwise, the output of previous run will be overriden.

answered Dec 30, 2018 at 16:31

Bsquare ℬℬ

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