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tmux new
( exit 0 )
res=echo $?
echo "exit
code:
$res"
( exit 255 )
res=$?
echo "exit code: $res"
# exit tmux session
exit |
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#!/bin/bash
# Script version global variable. Edit this whenever changes are made.
__ADVANCED_BASH_VERSION__="step_03"
# =======================================================================
# Helper functions
# =======================================================================
# Shorter format date
date2() { date '+%Y-%m-%d %H:%M'; }
# Echo's its arguments and the date to std error
echo_se() { echo "$@ - `date2`" 1>&2; }
maybe_echo() {
local do_echo=${ECHO_VERBOSE:-1}
if [[ "$do_echo" == "1" ]]; then echo_se "$@"; fi
}
# Sets up auto-logging to a log file in the current directory
# using the specified logFileTag (arg 1) in the log file name.
auto_log() {
local logFileTag="$1"
if [[ "$logFileTag" != "" ]]; then
local logFilePath="./autoLog_${logFileTag}.log"
maybe_echo ".. logging to $logFilePath"
exec 1> >(tee "$logFilePath") 2>&1
res=$?
if [[ "$res" != "0" ]]; then
echo_se "** ERROR: auto logging returned non-0 exit code $res"
exit 255
fi
else
echo_se "** ERROR in auto_log: no logFile argument provided"
exit 255
fi
}
# =======================================================================
# Command processing functions
# =======================================================================
# function that says "Hello World!" and displays user-specified text.
function helloWorld() {
local txt1=$1
local txt2=$2
shift; shift
local rest=$@
echo "Hello World!"
echo " text 1: '$txt1'"
echo " text 2: '$txt2'"
echo " rest: '$rest'"
}
# function that displays its 1st argument on standard output and
# its 2nd argument on standard error
function stdStreams() {
local outTxt=${1:-"text for standard output"}
local errTxt=${2:-"text for standard error"}
echo "to standard output: '$outTxt'"
echo_se "to standard error: '$errTxt'"
}
# function that illustrates auto-logging and capturing function output
# arg 1 - (required) tag to identify the logfile
# arg 2 - (optional) text for standard output
# arg 3 - (optional) text for standard error
function testAutolog() {
local logFileTag="$1"
local outTxt=${2:-"text for standard output"}
local errTxt=${3:-"text for standard error"}
auto_log "$logFileTag"
echo -e "\n1) Call stdStreams with output and error text:"
stdStreams "$outTxt" "$errTxt"
echo -e "\n2) Capture echo output in a variable and display it:"
local output=`echo $outTxt`
echo -e " echo output was:\n$output"
echo -e "\n3) Call echo_se with error text:"
echo_se "$errTxt"
echo -e "\n4)Capture echo_se function output in a variable and display it:"
output=`echo_se "$errTxt"`
echo -e "echo_se output was: '$output'"
}
# =======================================================================
# Main script command-line processing
# =======================================================================
function usage() {
echo "
advanced_bash.sh, version $__ADVANCED_BASH_VERSION__
Usage: advanced_bash.sh <command> [arg1 arg2...]
Commands:
helloWorld [text to display]
stdStreams [text for stdout] [text for stderr]
testAutolog <logFileTag> [text for stdout] [text for stderr]
"
exit 255
}
CMD=$1 # initially $1 will be the command
shift # after "shift", $1 will be the 2nd command-line argument; $2 the 3rd, etc.
# and $@ will be arguments 2, 3, etc.
# Only show usage if there is a command argument,
# making it possible to source this file
if [[ "$CMD" != "" ]]; then
case "$CMD" in
helloWorld) helloWorld "$@"
;;
stdStreams) stdStreams "$1" "$2"
;;
testAutolog) testAutolog "$1" "$2" "$3"
;;
*) usage
;;
esac
fi |
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CMD=$1 # initially $1 will be the command
shift # after "shift", $1 will be the 2nd command-line argument; $2 the 3rd, etc.
# and $@ will be arguments 2, 3, etc.
# Only show usage if there is a command argument,
# making it possible to source this file
if [[ "$CMD" != "" ]]; then
case "$CMD" in
helloWorld) helloWorld "$@"
;;
stdStreams) stdStreams "$1" "$2"
;;
testAutolog) testAutolog "$1" "$2" "$3"
;;
*) usage
;;
esac
fi |
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tmux new
source ~/workshop/step_03.sh
( helloWorld My name is Anna )
( stdStreams ) |
exercise 1
Test We can also test the new maybe_echo function, with and without verbose output:
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Code Block |
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tmux new
source ~/workshop/step_03.sh
# Normal verbose output
( maybe_echo "hello world" )
# Suppress verbose output
export ECHO_VERBOSE=0
( maybe_echo "hello world" )
# exit tmux session
exit |
auto_log function changes
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# Sets up auto-logging to a log file in the current directory
# using the specified logFileTag (arg 1) in the log file name.
auto_log() {
local logFileTag="$1"
if [[ "$logFileTag" != "" ]]; then
local logFilePath="./autoLog_${logFileTag}.log"
maybe_echo ".. logging to $logFilePath"
exec 1> >(tee "$logFilePath") 2>&1
res=$?
if [[ "$res" != "0" ]]; then
echo_se "** ERROR: auto logging returned non-0 exit code $res"
exit 255
fi
else
echo_se "** ERROR in autoLog: no logFile argument provided"
exit 255
fi
} |
exercise
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1
In a sub-shell, test the auto_log function – with and without a logFileTag argument – and check the exit code.
...