### Navigation

- index
- previous |
- unix tutorial 0.1 documentation »

# 2. Error messages

Errors are often a little confusing, so here are some common `Unix` and `AFNI` error messages, along with what they might imply.

## 2.1. Unix error messages

### 2.1.1. Command not found.

There are many ways one could accidentally get this error. It means the shell does not know of a command or program by the given name.

> 0. having a typo in the command name

> 1. the `$PATH` is not properly configureds, so the shell does not know about a given program

> 2. `rehash` is needed - a new program is in a `$PATH` directory, but the t-shell does not know about it (it is not in the hash table)

> 3. incorrect use of `\` characters at the end of some line(s)

>    The problem is on the line before the one mentioned in the error.

>    Line continuation `\` characters must be the final character on a given line, followed by a Unix newline character. Any misuse of it at the end of a line means the the will terminate the current command on that line, as well as consider any subsequent line the start of a new command. For example:

>        3dDeconvolve -input rall_vr+orig \
>           -concat concat_file.txt
>           -num_stimts 8                 \
>           ...

>    1. That leads to early termination of the `3dDeconvolve` command, which would make it fail (with or without error, depending on the options actually getting passed).

>    2. It would lead to a the shell viewing `-num_stimts 8` as the start of a new command, resulting in the error:

>           -stim_times: Command not found.

>    Note that spaces or tabs after any final `\` would also break the line coninuation interpretation, but they are difficult to see.

>    Also, non-Unix newline characters can be problematic.

>    For help with such things, consider `file_tool`, e.g.:

>        file_tool -test -infile my_script.txt

>    See also

>    file_tool -help

### 2.1.2. Undefined variable.

This error means no variable exists by the given name.

> 0. maybe there is a typo in the variable name
> 1. maybe the script author forgot to set the variable
> 2. maybe the variable was set in a child shell and does not exist in this context (or even in a different terminal window shell)

### 2.1.3. others - todo

> - No match.
> - ls: ...: No such file or directory

## 2.2. AFNI error messages

These are error messages that are specific to `AFNI` programs.

### 2.2.1. afni fails to open dataset

Some `AFNI` program failed to open or read a dataset.

### Navigation

- index
- previous |
- unix tutorial 0.1 documentation »