Bash judgement gets the unexpected result

Question

This is the code of the my shell script:

#! /bin/bash

if ["$SHELL" = "/bin/bash"];then
        echo "this is bash"
elif ["$SHELL" = "aa"];then
        echo "this is aa"
else
        echo "this is not /bin/bash, but $SHELL"
fi

why I execute the test_bash_03 script file gets the else result? shouldn't it be:this is bash ？

aircraftdeMacBook-Pro:bash_demo ldl$ ./test_bash_03
./test_bash_03: line 3: [/bin/bash: No such file or directory
./test_bash_03: line 5: [/bin/bash: No such file or directory
this is not /bin/bash, but /bin/bash

And I echo the $SHELL I also get the /bin/bash

aircraftdeMacBook-Pro:bash_demo ldl$ echo $SHELL
/bin/bash

Note those errors? It's because of them. Add space before and after your `[` and `]`. — RealSkeptic, Jul 19 '17 at 11:22
you can also use http://www.shellcheck.net/ to catch such typos and get other probable issues with script — Sundeep, Jul 19 '17 at 11:28
Note that `$SHELL` does *not* contain the name of the currently running shell; it contains the name of the user's "preferred" shell (which is usually interpreted to mean the user's default login shell). — chepner, Jul 19 '17 at 12:06

score 1 · Accepted Answer · answered Jul 19 '17 at 11:23

1

You are missing a space after [ and before ].

The bash tries to execute a command named [/bin/bash instead of [ (which is test), then doesn't find that and has an exit code of 1 (false). So you end up in the else case.

answered Jul 19 '17 at 11:23

Alfe

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Bash judgement gets the unexpected result

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