Bash - case statement always enters default

user_15300954 0
Viewed 364

I am writing a Bash script to parse a CSV file (values separated by ; character) and extract some arguments. Depending on the current argument read from the file a specific string is appended to a variable. However, the case statement always enters the default state *) and I can't figure out why.

I have no problems reading the .csv file. Already did that and displayed the output of the arguments read from the file. Everything works perfectly. The problem is that the case statement is not processed as expected.

So, the problem is not reading the .csv file but the processing of the arguments in the case statement.

This is my code:

while IFS=";" read -r arg
do
  case ${arg} in
    "valueX")
      var+="blabla"
      ;;
    "valueY")
      var+="blublu"
      ;;
    *)
      echo -e "Argument ${arg} not supported"
      exit 1
      ;;
  esac
done < filename

Assuming "valueX" is the current argument read from the file. Somehow the script always outputs:

Argument "valueX" not supported

Apparently, the argument (here: "valueX") read from the file is correct, but the script won't enter the corresponding state. Instead, it always enters the default state, no matter what value ${arg} holds.

[EDIT] I thought it would be a good idea to ask the question more generally, but it turns out to be confusing. So here is the full bash script and .csv file:

Script:

#!/bin/bash

# style reset
STYLE_RESET='\e[0m'
# Red foreground color
FOREGROUND_RED='\e[31m'
# Green foreground color
FOREGROUND_GREEN='\e[32m'
# Blue foreground color
FOREGROUND_BLUE='\e[34m'
# Red background color
BACKGROUND_RED='\e[41m'
# Green background color
BACKGROUND_GREEN='\e[42m'
# Blue background color
BACKGROUND_BLUE='\e[44m'

SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"


usage()
{
    echo "ToDo"
    exit 1
}
# --------------------------------------- #
# --- Checking Command Line Arguments --- #
# --------------------------------------- #
# Supported command line arguments:
#   -h|--help
#   -a|--address    IP of SSH server for remote VMAF
#   -u|--user       User for SSH server login
#   -d|--doe        DoE worksheet exported as CSV UTF-8 file
PARAMS=""
while (( "$#" )); do
    case "$1" in
        -h|--help)
            usage
            shift
            ;;
        -u|--user)
            if [ -n "$2" ] && [ ${2:0:1} != "-" ]; then # Check length of argument and first character of argument != '-'
                SSH_USER=$2
                shift 2
            else
                echo "Error: Argument for $1 is missing" >&2
                exit 1
            fi
            ;;
        -a|--address)
            if [ -n "$2" ] && [ ${2:0:1} != "-" ]; then # Check length of argument and first character of argument != '-'
                SSH_IP=$2
                shift 2
            else
                echo "Error: Argument for $1 is missing" >&2
                exit 1
            fi
            ;;
        -d|--doe)
            if [ -n "$2" ] && [ ${2:0:1} != "-" ]; then # Check length of argument and first character of argument != '-'
                DOE_FILE=$2
                shift 2
            else
                echo "Error: Argument for $1 is missing" >&2
                exit 1
            fi
            ;;
        -*|--*=) # unsupported flags
            echo "Error: Unsupported flag $1" >&2
            exit 1
            ;;
        *) # DEFAULT
            PARAMS="${PARAMS} $1" # preserve positional arguments
            shift
            ;;
    esac
done
# set positional arguments in their proper place
eval set -- "${PARAMS}"


# ---------------------- #
# --- Processing DoE --- #
# ---------------------- #
echo -e "${BACKGROUND_BLUE}Processing DoE specified in file ${DOE_FILE}:${STYLE_RESET}"
echo -e "${BACKGROUND_BLUE}Configuring Video source for GStreamer pipeline...${STYLE_RESET}"
GSTPIPE_SRC="gst-launch-1.0 -e "
run=1
while IFS=";" read -r motion bitrate_in bitrate_out twopass iframe quantI quantP quantB mvbuffer cabac vbv
do
    echo -e "\n\n${BACKGROUND_BLUE}Setting #${run}:${STYLE_RESET}"
    echo -e "${BACKGROUND_BLUE}${motion} ${bitrate_in} ${bitrate_out} ${twopass} ${iframe} ${quantI} ${quantP} ${quantB} ${mvbuffer} ${cabac} ${vbv}${STYLE_RESET}"
    echo -e "\n${BACKGROUND_BLUE}Generating GStreamer pipelines...${STYLE_RESET}"

    case ${motion} in
        "low")
            GSTPIPE_SRC+="videotestsrc pattern=colors num-buffers=300 ! " # -> no motion content
            case ${bitrate_in} in   # -> bitrate of video source (width*height*framerate)
                "low") # -> 640x480
                    GSTPIPE_SRC+="'video/x-raw, width=(int)640, height=(int)480, framerate=(fraction)30/1, format=(string)I420' "
                    width=640
                    height=480
                    fps=30
                    ;;
                "high") # -> 3840x2160
                    GSTPIPE_SRC+="'video/x-raw, width=(int)3840, height=(int)2160, framerate=(fraction)30/1, format=(string)I420' "
                    width=3840
                    height=2160
                    fps=30
                    ;;
                *)
                    echo -e "\n\n${BACKGROUND_RED}Input bitrate ${bitrate_in} not supported${STYLE_RESET}"
                    echo -e "Use low, or high instead"
                    exit 1
                    ;;
            esac
            ;;
        "high")
            GSTPIPE_SRC+="filesrc location=${SCRIPT_DIR}/extensive.mp4 " # -> high motion content
            case ${bitrate_in} in   # -> bitrate of video source (width*height*framerate)
                "low") # -> 640x480
                    GSTPIPE_SRC+="blocksize=460800 ! " # blocksize=width*height*bytesPerPixel (I420->12bit->bytesPerPixel=1.5)
                    GSTPIPE_SRC+="'video/x-raw, width=(int)640, height=(int)480, framerate=(fraction)30/1, format=(string)I420' "
                    width=640
                    height=480
                    fps=30
                    ;;
                "high") # -> 3840x2160
                    GSTPIPE_SRC+="blocksize=12441600 ! " # blocksize=width*height*bytesPerPixel (I420->12bit->bytesPerPixel=1.5)
                    GSTPIPE_SRC+="'video/x-raw, width=(int)3840, height=(int)2160, framerate=(fraction)30/1, format=(string)I420' "
                    width=3840
                    height=2160
                    fps=30
                    ;;
                *)
                    echo -e "\n\n${BACKGROUND_RED}Input bitrate ${bitrate_in} not supported${STYLE_RESET}"
                    echo -e "Use low, or high instead"
                    exit 1
                    ;;
            esac
            ;;
        *)
            echo -e "${BACKGROUND_RED}Argument ${motion} for DoE factor 'motion' not supported${STYLE_RESET}"
            echo -e "Use low, or high instead"
            exit 1
            ;;
    esac

    GSTPIPE_ENC=$GSTPIPE_SRC
    GSTPIPE_REF=$GSTPIPE_SRC

    GSTPIPE_REF+="! y4menc ! filesink location=${SCRIPT_DIR}/reference${fps}fps_run${run}.y4m"

    GSTPIPE_ENC+="! nvvidconv ! 'video/x-raw(memory:NVMM)' ! nvv4l2h264enc "
    GSTPIPE_ENC+="bitrate=${bitrate_out} EnableTwopassCBR=${twopass} "
    case ${iframe} in
        "low")
            GSTPIPE_ENC+="iframeinterval=20 SliceIntraRefreshInterval=10 "
            ;;
        "high")
            GSTPIPE_ENC+="iframeinterval=120 SliceIntraRefreshInterval=60 "
            ;;
        *)
            echo -e "${BACKGROUND_RED}Argument ${motion} for DoE factor iframe is not supported${STYLE_RESET}"
            echo -e "Use low, or high instead"
            exit 1
            ;;
    esac
    # The range of B frames does not take effect if the number of B frames is 0. (https://docs.nvidia.com/jetson/l4t/index.html#page/Tegra%20Linux%20Driver%20Package%20Development%20Guide/accelerated_gstreamer.html#wwpID0E0YX0HA)
    GSTPIPE_ENC+="quant-i-frames=${quantI} quant-p-frames=${quantP} quant-b-frames=${quantB} num-b-frames=1 EnableMVBufferMeta=${mvbuffer} cabac-entropy-coding=${cabac} "
    GSTPIPE_ENC+="! nvv4l2decoder ! nvvidconv ! 'video/x-raw' ! y4menc ! filesink location=${SCRIPT_DIR}/distorted${fps}fps_run${run}.y4m"
    echo -e "${BACKGROUND_BLUE}Distorted Video:${STYLE_RESET}"
    echo -e "${FOREGROUND_BLUE}${GSTPIPE_ENC}${STYLE_RESET}"
    echo -e "${BACKGROUND_BLUE}Reference Video:${STYLE_RESET}"
    echo -e "${FOREGROUND_BLUE}${GSTPIPE_REF}${STYLE_RESET}"

    # --- Launching GStreamer pipelines (surpress detailed output) --- #
    echo -e "${BACKGROUND_BLUE}Launching GStreamer pipeline for encoded video (distorted):${STYLE_RESET}"
    eval "${GSTPIPE_ENC[@]}" #> /dev/null
    echo -e "${BACKGROUND_BLUE}Launching GStreamer pipeline for uncompressed video (reference):${STYLE_RESET}"
    eval "${GSTPIPE_REF[@]}" #> /dev/null

    # --- Create and Check Remote Directories --- #
    echo -e "\n${BACKGROUND_BLUE}Video transfer to remote machine:${STYLE_RESET}"
    SSH_DIR_ADD="v4l2h264/motion_${motion}/bitrate_${bitrate_in}/"
    SSH_DIR="/home/${SSH_USER}/metrics/${SSH_DIR_ADD}"  # Create variable holding path of directory for both:
                                                    #   1.) reference.y4m and distorted.y4m videos
                                                    #   2.) remote VMAF
    ssh ${SSH_USER}@${SSH_IP} "test -d ${SSH_DIR}" < /dev/null # see https://stackoverflow.com/questions/9393038/ssh-breaks-out-of-while-loop-in-bash
    if [ $? -ne 0 ]; then # Directory does not exist
        echo -e "${BACKGROUND_BLUE}Creating remote directory for run #${run}: ${SSH_DIR}...${STYLE_RESET}"
        ssh ${SSH_USER}@${SSH_IP} "mkdir -p ${SSH_DIR}" < /dev/null # see https://stackoverflow.com/questions/9393038/ssh-breaks-out-of-while-loop-in-bash
    else # Directory already exists
        echo -e "${BACKGROUND_BLUE}Remote directory ${SSH_DIR} already exists${STYLE_RESET}"
    fi

    # --- Transfer Video Files --- #
    echo -e "${BACKGROUND_BLUE}Transfering reference and distorted videos of run #${run}:${STYLE_RESET}"
    scp ${SCRIPT_DIR}/distorted${fps}fps_run${run}.y4m ${SSH_USER}@${SSH_IP}:${SSH_DIR} < /dev/null # see https://stackoverflow.com/questions/9393038/ssh-breaks-out-of-while-loop-in-bash
    scp ${SCRIPT_DIR}/reference${fps}fps_run${run}.y4m ${SSH_USER}@${SSH_IP}:${SSH_DIR} < /dev/null # see https://stackoverflow.com/questions/9393038/ssh-breaks-out-of-while-loop-in-bash

    # --- Run VMAF on Remote Machine --- #
    echo -e "\n${BACKGROUND_BLUE}Running VMAF metric for DoE run #${run} on remote machine...${STYLE_RESET}"
    ssh ${SSH_USER}@${SSH_IP} "vmaf -r ${SSH_DIR}/reference${fps}fps_run${run}.y4m -d ${SSH_DIR}/distorted${fps}fps_run${run}.y4m -w ${width} -h ${height} -p 420 -b 12 -o ${SSH_DIR}/log${fps}fps_run${run}.xml --threads 8" < /dev/null # see https://stackoverflow.com/questions/9393038/ssh-breaks-out-of-while-loop-in-bash
    echo -e "${BACKGROUND_BLUE}VMAF metric for DoE run #${run} finished.${STYLE_RESET}"

    # --- Remove Videos on Remote Machine (Laptop) --- #
    echo -e "\n${BACKGROUND_BLUE}Removing videos from remote machine${STYLE_RESET}"
    ssh ${SSH_USER}@${SSH_IP} "rm ${SSH_DIR}/distorted${fps}fps_run${run}.y4m ${SSH_DIR}/reference${fps}fps_run${run}.y4m" < /dev/null # see https://stackoverflow.com/questions/9393038/ssh-breaks-out-of-while-loop-in-bash

    # --- Remove videos on local machine (SPU) --- #
    echo -e "\n${BACKGROUND_BLUE}Removing videos from local machine${STYLE_RESET}"
    rm distorted${fps}fps_run${run}.y4m reference${fps}fps_run${run}.y4m

    ((run++))

done < <(cut -d ";" -f5,6,7,8,9,10,11,12,13,14,15,16 ${DOE_FILE} | tail -n +2) # read from the second line of the file (no header) and only read the columns specified with -f
((run--))

exit 0

.csv file:

"StdOrder";"RunOrder";"CenterPt";"Blocks";"motion";"bitrate_in";"bitrate_out";"twopass";"iframe";"quantI";"quantP";"quantB";"mvbuffer";"cabac"
1;1;1;1;"low";"low";200000;"false";"low";0;0;0;"true";"true"
6;2;1;1;"high";"low";80000000;"false";"low";51;0;51;"true";"false"
8;3;1;1;"high";"high";80000000;"false";"high";0;0;0;"false";"true"
2;4;1;1;"high";"low";200000;"false";"high";0;51;51;"false";"false"
3;5;1;1;"low";"high";200000;"false";"high";51;0;51;"false";"false"
7;6;1;1;"low";"high";80000000;"false";"low";0;51;51;"true";"false"
10;7;1;1;"high";"low";200000;"true";"high";51;0;0;"true";"false"
9;8;1;1;"low";"low";200000;"true";"low";51;51;51;"false";"true"
4;9;1;1;"high";"high";200000;"false";"low";51;51;0;"true";"true"
13;10;1;1;"low";"low";80000000;"true";"high";0;0;51;"true";"true"
5;11;1;1;"low";"low";80000000;"false";"high";51;51;0;"false";"true"
12;12;1;1;"high";"high";200000;"true";"low";0;0;51;"false";"true"
15;13;1;1;"low";"high";80000000;"true";"low";51;0;0;"false";"false"
14;14;1;1;"high";"low";80000000;"true";"low";0;51;0;"false";"false"
16;15;1;1;"high";"high";80000000;"true";"high";51;51;51;"true";"true"
11;16;1;1;"low";"high";200000;"true";"high";0;51;0;"true";"false"
while-loop case bash
2 Answers

Apparently, the argument (here: "valueX") read from the file is correct

Since you consider the quotes being part of the argument to be correct, in order to match them with a case pattern, you have to escape the pattern quotes:

  case ${arg} in
    \"valueX\")

Interestingly, this appears to be a Bash (documentation) error, as that says only:

Each pattern undergoes tilde expansion, parameter expansion, command substitution, and arithmetic expansion.

It doesn't tell that the pattern undergoes quote removal.

user_24132010

None of your sample data contains valueX, but assuming you were looking for e.g. "high" in the fifth field, you need to ask the shell to split into at least six fields;

while IFS=";" read -r _first _second _third _fourth arg _rest
do
  case ${arg} in
    '"high"')
      var+="blabla"
      ;;
    '"low"')
      var+="blublu"
      ;;
    *)
      echo -e "Argument ${arg} not supported"
      exit 1
      ;;
  esac
done < filename

Probably a better solution here is to use Awk, though.

awk -F ';' '$5 !~ /"(high|low)"/ { print "Argument " $5 " is not supported" }' filename

Without the rest of your script, it's hard to tell in which direction to continue this; very often, if you are using Awk anyway, it makes sense to implement the rest of the logic in Awk, too.

user_8741880
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