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Top Forums Shell Programming and Scripting Chunks of bash shell programming Post 302852405 by verdepollo on Wednesday 11th of September 2013 01:10:33 PM
Old 09-11-2013
This looks almost like homework so I'm not gonna go into much details. If you have any specific questions post them back here.

1. Expand the variable "DEBUG" *if, and only if* it's already defined, else use zero.
2. Print the contents of the first script argument.
3. Defines a function that checks if a file does not exist. "tee" is a specific purpose command; Take a look at the man page (man tee).
4. Defines another function that checks if the contents of $DEBUG aren't equal to 1 (numeric value, not string).
5. String assignment.
6. "-z" is a comparison operator used to tell if string has zero length.

In all cases the syntax ${var} is used to "protect" the variables. E.g:
Code:
var1="asdf"
echo "${var1}2"
echo "$var12"

One of the above "echo" statements will work fine and the other will throw an error. Try it for yourself to find out which one fails and why. Smilie
 

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ATF-SH(1)						    BSD General Commands Manual 						 ATF-SH(1)

NAME
atf-sh [-s shell] -- interpreter for shell-based test programs SYNOPSIS
atf-sh script DESCRIPTION
atf-sh is an interpreter that runs the test program given in script after loading the atf-sh(3) library. atf-sh is not a real interpreter though: it is just a wrapper around the system-wide shell defined by ATF_SHELL. atf-sh executes the inter- preter, loads the atf-sh(3) library and then runs the script. You must consider atf-sh to be a POSIX shell by default and thus should not use any non-standard extensions. The following options are available: -s shell Specifies the shell to use instead of the value provided by ATF_SHELL. ENVIRONMENT
ATF_LIBEXECDIR Overrides the builtin directory where atf-sh is located. Should not be overridden other than for testing purposes. ATF_PKGDATADIR Overrides the builtin directory where libatf-sh.subr is located. Should not be overridden other than for testing purposes. ATF_SHELL Path to the system shell to be used in the generated scripts. Scripts must not rely on this variable being set to select a specific interpreter. EXAMPLES
Scripts using atf-sh(3) should start with: #! /usr/bin/env atf-sh Alternatively, if you want to explicitly choose a shell interpreter, you cannot rely on env(1) to find atf-sh. Instead, you have to hardcode the path to atf-sh in the script and then use the -s option afterwards as a single parameter: #! /path/to/bin/atf-sh -s/bin/bash ENVIRONMENT
ATF_SHELL Path to the system shell to be used in the generated scripts. SEE ALSO
atf-sh(3) BSD
September 27, 2014 BSD
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