process exit - 127 Return code from $?

docker error: (7)

What is the meaning of return value 127 from $? in UNIX.


Value 127 is returned by /bin/sh when the given command is not found within your PATH system variable and it is not a built-in shell command. In other words, the system doesn't understand your command, because it doesn't know where to find the binary you're trying to call.

It has no special meaning, other than that the last process to exit did so with an exit status of 127.

However, it is also used by bash (assuming you're using bash as a shell) to tell you that the command you tried to execute couldn't be executed (i.e. it couldn't be found). It's unfortunately not immediately deducible though, if the process exited with status 127, or if it couldn't found.

Not immediately deducible, except for the output on the console, but this is , so I assume you're doing this in a script.

127 - command not found

example: $caat The error message will


caat: command not found

now you check using echo $?

If you're trying to run a program using a scripting language, you may need to include the full path of the scripting language and the file to execute. For example:

exec('/usr/local/bin/node /usr/local/lib/node_modules/uglifycss/uglifycss in.css > out.css');

This error is also at times deceiving. It says file is not found even though the files is indeed present. It could be because of invalid unreadable special characters present in the files that could be caused by the editor you are using. This link might help you in such cases.

-bash: ./my_script: /bin/bash^M: bad interpreter: No such file or directory

The best way to find out if it is this issue is to simple place an echo statement in the entire file and verify if the same error is thrown.

Generally it means:

127 - command not found

but it can also mean that the command is found,
but a library that is required by the command is NOT found.

The answer to run valgrind --tool=callgrind is not quite complete without some options. We usually do not want to profile 10 minutes of slow startup time under Valgrind and want to profile our program when it is doing some task.

So this is what I recommend. Run program first:

valgrind --tool=callgrind --dump-instr=yes -v --instr-atstart=no ./binary > tmp

Now when it works and we want to start profiling we should run in another window:

callgrind_control -i on

This turns profiling on. To turn it off and stop whole task we might use:

callgrind_control -k

Now we have some files named callgrind.out.* in current directory. To see profiling results use:

kcachegrind callgrind.out.*

I recommend in next window to click on "Self" column header, otherwise it shows that "main()" is most time consuming task. "Self" shows how much each function itself took time, not together with dependents.