Bash script: "[[: not found"

This is my code:

#!/bin/bash if [[ -d ~/viwiki ]]; then cd ~/viwiki else mkdir ~/viwiki cd ~/viwiki fi if ! [[ -d ./log ]]; then mkdir log mkdir log/log mkdir "log/wget" elif ! [[ -d ./log/log ]]; then mkdir log/log elif ! [[ -d "./log/wget" ]]; then mkdir "log/wget" fi 

When running, it has errors:

tuankiet65@UbuntuPC:~$ sh viwik/test2.sh viwik/test2.sh: 2: viwik/test2.sh: [[: not found viwik/test2.sh: 8: viwik/test2.sh: [[: not found 

How can I fix this?

1 Answer

I'm guessing that if you run

readlink -f $(which sh) 

you will not get Bash as return value, but Dash. You have the correct preamble, but that only matters if you run the script as ./test2.sh after making it executable.

Right now you force-run the script via the sh interpreter, which probably is Dash, and the [[]] construct is a Bash specific one.

That's "why?". If you just replace the double brackets with single ones (and change #!/bin/bash to #!/bin/sh, since your script is now only using POSIX functions anyway) it should run as intended.

Demonstration on Debian, with test.sh with contents:

#!/bin/bash if [[ "string" == "string" ]]; then echo This is Bash fi 

this happens:

$ readlink -f $(which sh) /bin/dash $ sh test.sh test.sh: 2: test.sh: [[: not found $ bash test.sh This is Bash $ chmod 755 test.sh $ ./test.sh This is Bash