Ignoring specific errors in a shell script
bash, error-handling, shell
Solution
In order to cause bash to ignore errors for specific commands you can say:
some-arbitrary-command || true
This would make the script continue. For example, if you have the following script:
$ cat foo
set -e
echo 1
some-arbitrary-command || true
echo 2
Executing it would return:
$ bash foo
1
z: line 3: some-arbitrary-command: command not found
2
In the absence of `|| true` in the command line, it'd have produced:
$ bash foo
1
z: line 3: some-arbitrary-command: command not found
Quote from the manual:
The shell does not exit if the command that fails is part of the command list immediately following a `while` or `until` keyword, part of the test in an `if` statement, part of any command executed in a `&&` or `||` list except the command following the final `&&` or `||`, any command in a pipeline but the last, or if the command’s return status is being inverted with `!`. A trap on `ERR`, if set, is executed before the shell exits.
EDIT: In order to change the behaviour such that in the execution should continue only if executing `some-arbitrary-command` returned `file not found` as part of the error, you can say:
[[ $(some-arbitrary-command 2>&1) =~ "file not found" ]]
As an example, execute the following (no file named `MissingFile.txt` exists):
$ cat foo
#!/bin/bash
set -u
set -e
foo() {
rm MissingFile.txt
}
echo 1
[[ $(foo 2>&1) =~ "No such file" ]]
echo 2
$(foo)
echo 3
This produces the following output:
$ bash foo
1
2
rm: cannot remove `MissingFile.txt': No such file or directory
Note that `echo 2` was executed but `echo 3` wasn't.
Problem
I have a small snippet of a shell script which has the potential to throw many errors. I have the script currently set to globally stop on all errors. However i would like for this small sub-section is slightly different. Here is the snippet: ``` recover database using backup controlfile until cancel || true; auto ``` I'm expecting this to eventually throw a "file not found" error. However i would like to continue executing on this error. For any other error i would like the script to stop. What would be the best method of achieving this? Bash Version 3.00.16