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POSIX Shell Functions

This document contains all information that's generic to all shell functions as well as basic descriptions of what each script does. For more detailed information regarding usage of a script, either open the file that contains the script or, if you've already setup your environment, then in your terminal enter: <scriptName> -h or <scriptName> --help.

Return Codes

The table bellow defines what the meaning of each return value. For details regarding what exactly might have caused a given return code to be returned, check the log produced above the doc that's printed to stderr for a log that describes what caused the off nominal code. Alternatively, enter <funcationName> --help for a document that describes how to use the function of intrest.

Code Returned When Example Note(s)
0
  • Help message is requested and produced.
  • Processing is successfull.
1 POSIX Standard: Catchall for general errors let "var1 = 1/0" https://tldp.org/LDP/abs/html/exitcodes.html
2 POSIX Standard: Misuse of shell builtins (according to Bash documentation) empty_function() {} https://tldp.org/LDP/abs/html/exitcodes.html
3 Failed to execute, but it's not that bad. Failed to change file, but reverted it.
4 Failed to execute, and it is that bad. Failed to change file & to revert it.
126 POSIX Standard: Command invoked cannot execute /dev/null https://tldp.org/LDP/abs/html/exitcodes.html
127 POSIX Standard: command not found illegal_command https://tldp.org/LDP/abs/html/exitcodes.html
128 POSIX Standard: Invalid argument to exit exit 3.14159 https://tldp.org/LDP/abs/html/exitcodes.html
128+n POSIX Standard: Fatal error signal "n" kill -9 $PPID of script https://tldp.org/LDP/abs/html/exitcodes.html
130 POSIX Standard: Script terminated by Control-C Ctl-C https://tldp.org/LDP/abs/html/exitcodes.html
131 Control-C is handled prior to exiting or user chooses to exit through the UI.
140 A provided option name is invalid. Codes in the 14Xs relate to options.
141 A provided option value is invalid.
142 A required option is not provided.
151 A provided argument value is invalid. Codes in the 15Xs relate to arguments.
152 A required argument is not provided.
160 Required file doesn't exist. Codes in the 16Xs relate to file access.
161 Failed to create a file.
162 Failed to remove file.
163 File already exists.
164 File doesn't already exist or can't be found/accessed.
165 Failed to move/rename file.
166 Failed to copy file.
167 Failed to open file.
168 Failed read from file.
169 Failed to write to file.
170 Required directory doesn't exist. Codes in the 17Xs relate to directory access.
171 Failed to create a directory.
172 Failed to remove directory.
173 Directory already exists.
174 Directory doesn't already exist or can't be found/accessed.
175 Failed to move/rename directory.
176 Failed to copy directory.
177 Failed to enter directory.
180 Code not run from same directory it's located in. Codes in the 18Xs relate to the location code is run from.
181 Code not run from user's home directory.
182 Code not run from the correct directory (generic version of other codes).
190 Code sourced when it shouldn't be. Codes in the 19Xs relate to how the code is envoked.
191 Code isn't sourced when it should be.
192 Code not run by/as root when it should be.
193 Code run as/by root when it shouldn't be.
194 Code run by incorrect user.
200 Environment variable(s) set to unsupported value. Codes in the 20Xs relate to environment setup.
201 Environment variable(s) not set.
202 Requried script/function not accessible (doesn't exist at expected path, isn't sourced, etc).
203 Required system commands not accessible.
209 Any other environment issue.
255 POSIX Standard: Exit status out of range exit -1 https://tldp.org/LDP/abs/html/exitcodes.html

POSIX Functions

backUp

Script that copies files and directories from user's home directory to another location.

verifyInputProvided

Used by other scripts to ensure that all option(s) passed into it are valid (contain something). If that's not the case, then the calling scripts doc is produced to std out.

log

Produces formatted logs to stdout.

log Example Usage

infoLvl="-i -c=example_script"
readonly infoLvl

log $infoLvl -m="Requesting input from user..."
printf "Enter number you'd like to count to: "
read userVar
log $infoLvl -m="User entered: '$userVar'"

for (( i=1; i<=$userVar; i++)); do
	log $infoLvl -m="$i"
done

output

Used to add pre-fix, post-fix, headers, and/or footers to message text. Used by log()'s title options.

shellName

Returns the name of the shell that called the script to stdout.