BASH - String output is not what I expected

Question

I have a situation where I need to echo:

a variable - plain text - the result of a function call

Im so confused about what the various symbols mean when echoing

Here are my functions:

#!/bin/bash

getLogTimestamp() {
    echo $(date +%Y-%m-%dT%H:%M:%S.130Z)
}

getDisplayName(){
echo $(awk -F'=' '/^CARBON_LITE_PLAYER_ID=.*/ { print $2;}' /home/benja/app/.env)
}

getDeviceIPAddress(){
echo $(hostname -i)
}

getSystemUptime(){
echo $(uptime)
}

getDateTimeInfo(){
echo "$(timedatectl status | awk '/Warning/{exit} 1')"
}

getMemoryInfo() {
    arr=( $(free -h) )
    keys=("${arr[@]::8}")
    vals=("${arr[@]:8:12}")
    for i in ${!keys[@]}; { printf -v data[i] "%s: %s, " "${keys[i]}" "${vals[i]}"; }
    data="${data[@]}"
    echo ${data%,*}
}

getDiskInfo()
{
  arr=($(df -h))
    keys=("${arr[@]::6}")
    vals=("${arr[@]:7:100}")
    for i in ${!keys[@]}; { printf -v data[i] "%s: %s, " "${keys[i]}" "${vals[i]}"; }
    data="${data[@]}"
    echo ${data%,*}
}

getDisplayState(){
    STATE=$(/opt/vc/bin/tvservice -s | awk '/state/  {print $2}')

    case $STATE in

    $STATE=0x40001 )
            echo VC_SDTV_NTSC, VC_HDMI_UNPLUGGED 
            ;;
    $STATE=0x40002 )
            echo VC_SDTV_NTSC, VC_HDMI_ATTACHED
            ;;
    $STATE=0x120002 )
            echo VC_SDTV_ATTACHED, VC_SDTV_CP_INACTIVE, VC_HDMI_ATTACHED
            ;;
    $STATE=0x120005 )
            echo VC_SDTV_ATTACHED, VC_SDTV_CP_INACTIVE, VC_HDMI_UNPLUGGED, VC_HDMI_DVI
            ;;
    $STATE=0x120016 )
            echo VC_SDTV_ATTACHED, VC_SDTV_CP_INACTIVE, VC_HDMI_ATTACHED, VC_HDMI_DVI, VC_HDMI_HDCP_UNAUTH
            ;;
    $STATE=0x12001a )
            echo VC_SDTV_ATTACHED, VC_SDTV_CP_INACTIVE, VC_HDMI_ATTACHED, VC_HDMI_HDMI, VC_HDMI_HDCP_UNAUTH
            ;;
    $STATE=0x12001a )
            echo VC_SDTV_ATTACHED, VC_SDTV_CP_INACTIVE, VC_HDMI_ATTACHED, VC_HDMI_HDMI
            ;;
    $STATE=0x120009 )
            echo  VC_SDTV_ATTACHED, VC_SDTV_CP_INACTIVE, VC_HDMI_UNPLUGGED, VC_HDMI_HDMI
            ;;
    esac
}

In a separate file I am calling these functions:

#Logging
. /home/benja/app/scripts/log-helper-functions.sh
LOGTIMESTAMP=getLogTimestamp

# RSH -We are logging this data every time this script runs (chron job)

echo $LOGTIMESTAMP "Display Name: $(getDisplayName)"

echo $LOGTIMESTAMP "Device IP: $(getDeviceIPAddress)"

echo $LOGTIMESTAMP "System UpTime: $(getSystemUptime)"

echo $LOGTIMESTAMP "DateTime Info: $(getDateTimeInfo)"

echo $LOGTIMESTAMP "Memory Info: $(getMemoryInfo)"

echo $LOGTIMESTAMP "Disk Info: $(getDiskInfo)"

echo $LOGTIMESTAMP "Display State: $(getDisplayState)"

# RSH end

This is an example of the output:

getLogTimestamp Display Name: UAT-101429
getLogTimestamp Device IP: 10.0.0.120
getLogTimestamp System UpTime: 23:26:06 up 19:54, 1 user, load average: 1.66, 0.82, 0.47
getLogTimestamp DateTime Info:       Local time: Thu 2020-04-09 23:26:06 EDT
  Universal time: Fri 2020-04-10 03:26:06 UTC
        RTC time: n/a
       Time zone: America/New_York (EDT, -0400)
 Network time on: yes
NTP synchronized: no
 RTC in local TZ: yes
getLogTimestamp Memory Info: total: 174M, used: 42M, free: 91M, shared: 388M, buff/cache: 317M, available: Swap:, Mem:: 0B, 605M: 0B
getLogTimestamp Disk Info: Filesystem: /dev/root, Size: 30G, Used: 4.6G, Avail: 23G, Use%: 17%, Mounted: /
getLogTimestamp Display State:

Problems: Obviously the $TIMESTAMP is not resolving, and the Display State is not resolving.

What am I doing wrong?

TIA -Ron

The variable assignment in bash does not allow the $ on the left hand side, afaik the only way it will work is using infamous eval , or I'm just imagining things :-) — Jetchisel
– Jetchisel, Commented Apr 14, 2020 at 12:10
@Jetchisel : I don't see any $VAR=value error. If you think of the $STATE=0x40001 stuff, these are supposed to be wildcard patterns matched by case, not assignments. Still, the case doesn't look right, but for different reasons. — user1934428
– user1934428, Commented Apr 14, 2020 at 12:16

choroba · Accepted Answer · 2020-04-14 12:14:51Z

2

The right hand side of an assignment doesn't normally run. You need to tell bash to run it and use the output:

LOGTIMESTAMP=$(getLogTimestamp)

The case statement has a different syntax. Each case consists of just the value, you already stated the $STATE in the case $STATE line, no need to repeat it on each line.

case "$STATE" of
    0x40001) ...

answered Apr 14, 2020 at 12:14

choroba

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2 Comments

RSH Over a year ago

Ah gotcha! Now the $LOGTIMESTAMP is showing correctly, but the DisplayState is still empty: 2020-04-10T00:04:35.130Z - Display State:

RSH Over a year ago

getDisplayState(){ STATE=$(/opt/vc/bin/tvservice -s | awk '/state/ {print $2}') case $STATE in 0x40001) echo VC_SDTV_NTSC, VC_HDMI_UNPLUGGED ;; ...

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