Bash variable substitution in a function - regex

I have a function read_command defined as:
function read_command {
local __newline __lines __input __newstr __tmp i;
exec 3< "$*";
__newline=$'\n';
__lines=();
while IFS= read <&3 -r __line && [ "$__line" != '####' ]; do
echo "$__line";
__lines+=("$__line");
done
while IFS= read <&3 -r __line && [ "$__line" != '####' ]; do
read -e -p "${__line#*:}$PS2" __input;
local ${__line%%:*}="$__input";
done
__command="";
for i in "${__lines[#]}"; do
__tmp=$(echo "${i}");
__command="${__command} ${__newline} ${__tmp}";
done
echo -e "$__command";
}
In the current directory there is a file named "test", with the following
content:
greet ${a:-"Bob"}
greet ${b:-"Jim"}
####
a: name of friend a
b: name of friend b
####
In the terminal, the command executed is
read_command test
With no input, I am expecting the output of the last statement to be:
greet Bob
greet Jim
But what I get is:
greet ${a:-"Bob"}
greet ${b:-"Jim"}
What is wrong here?
Edit: As suggested by David, adding eval works in some cases except the following one.
j=1;i="export DISPLAY=:0 && Xephyr :${j}&";k=$(eval echo "$i");
echo $k
export DISPLAY=:0
I am expecting k to be "export DISPLAY=:0 && Xephyr :1&", what's wrong here?
Edit: I tried with the following
k=$(eval "echo \"$i\"")
This is the link to the script I am working on.
https://gist.github.com/QiangF/565102ba3b6123942b9bf6b897c05f87

During the first while loop, in echo "$__line", you have __line='greet ${a:-"Bob"}'. When you try to print that, Bash won't be expanding ${a:-"Bob"} into Bob. (Even if you remove the quotes around $__line this won't happen.) To get that effect, you need to add eval, as in, e.g., eval echo "$__line". Unfortunately eval comes with its can of worms, you have to start worrying about interactions between quoting levels and such.

Related

Creating an alert function in Bash

I wanted to create a function in bash similar to a default alias I got in Ubuntu, looking like:
alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
This creates a simple notification after a command has been issued with it.
For example, using
history | grep vim; sleep 5; alert
gives a notification after the sleep is done, simply saying
history | grep vim; sleep 5;
I would like to write the alert into a bash function instead, which have given some trouble with the regex.
I have tried:
function alert2 () {
ICON=$([ $? = 0 ] && echo terminal || echo error)
MSG=$(history | tail -n1 | sed -e s/^\s*[0-9]\+\s*//\;s/[\;\&\|]\s*alert$//)
notify-send --urgency=low -i $ICON $MSG
}
which would output both the linenumber in history when called itself, and give an Invalid number of options when called such as the first example.
Is this possible, and if so, how? Is it simply my regex that is faulty?
I'm running on WSL, so don't have notify-send installed:
function alert2 () {
ICON=$([ $? = 0 ] && echo terminal || echo error);
MSG=$(history | tail -n1| sed -e 's/^\s*[0-9]\+\s*//;s/[;&|]\s*alert2$//');
echo $ICON $MSG;
}
jadams#Temp046317:~/code/data-extract$ cat /etc/apt/sources.list > /dev/null ; alert2
terminal cat /etc/apt/sources.list > /dev/null
I'm hoping that this would work for you (instead of the echo):
notify-send --urgency=low -i "$ICON $MSG"

How can I get the return value of `wget` from a sh script into an `int` variable

OS: Linux raspberrypi 4.19.58-v7l+ #1245 SMP Fri Jul 12 17:31:45 BST 2019 armv7l GNU/Linux
Board: Raspberry Pi 4
I have a script:
#!/bin/bash
line=$(head -n 1 /var/www/html/configuration.txt)
file=/var/www/html/4panel/url_response.txt
if [ -f "$file" ]; then
wget_output=$(wget -q -i "$line" -O $file --timeout=2)
echo "$?"
else
echo > $file
chown pi:pi $file
fi
which I call from a C++ program using:
int val_system = 0;
val_system = system("/var/www/html/4panel/get_page.sh");
std::cout<<"System return value: "<<val_system<<std::endl;
If there is something wrong with the script, echo "$?" will output the return value of wget, but val_system will always be 0.
Does system() returns the value of echo "$?" ? In which case 0 is correct. And if that is the case how can I put the return value of wget in val_system ?
I have taken a situation in which echo "$?" always returns 8, basically I've entered an incorrect URL and:
I have tried deleting echo "$?" but val_system still returned 0;
With echo "$?" deleted I have changed the wget line to wget -q -i "$line" -O $file --timeout=2 and val_system now returns 2048.
None of my attempts bared any fruit and I have come here to seek guidance. How can I make val_system / system() return what echo "$?" returns ?
How can I get the return value of wget from the script into an int variable that's inside the C++ program that calls the script ?
The integer value system() returned contains extra information about executed command's status along with its exit code, see system() and Status Information. You need to extract exit code using WEXITSTATUS macro, like:
std::cout << "System return value: " << WEXITSTATUS(val_system) << std::endl;
If you want to echo the status and return it, you will need to save the value of $? to a variable, and exit with it explicitly.
wget_output=$(wget -q -i "$line" -O $file --timeout=2)
status=$?
...
echo $status
...
exit $status
If you don't need to execute echo or any other command between the call to wget and the end of the script, you can rely on the script exiting with the last status (i.e the one corresponding to the call to `wget) implicitly.

I get syntax error when i call script from c++ program

I'm trying to write a program that will allow easier management of Arduino projects. So I wrote bash script that creates all the necessary folders and files for me and when I execute it I runs like champ. Because I want to change directory in the working terminal inside the script I run script like this
. ./initialize.sh
This is also working great, but because I am writing C++ program, sourcing this script from program is giving me headache.
So inside a program I run this script like this:
system(". /usr/lib/avrduino/script/initialize.sh");
and then when I run the program I get this error:
sh: 25: /usr/lib/avrduino/script/initialize.sh: Syntax error: "(" unexpected (expecting "}")
Running the script from the program like this:
system("/usr/lib/avrduino/script/initialize.sh");
works without error but it runs in subshell.
Syntax error points to this line in script
options=("uno" "mega" "mega2560" "atmega8" "atmega168" "atmega328" "pro" "pro5v" "pro328" "pro5v328")
How come that when I run this script outside of the program it's working like champ, but run this script from program and you have a problem ?
EDIT:
Script code
#!/bin/bash
BLACK='\033[0;30m'
RED='\033[0;31m'
GREEN='\033[0;32m'
BROWN='\033[0;33m'
BLUE='\033[0;34m'
PURPLE='\033[0;35m'
CYAN='\033[0;36m'
LGRAY='\033[0;37m'
DGRAY='\033[1;30m'
LRED='\033[1;31m'
LGREEN='\033[1;32m'
YELLOW='\033[1;33m'
LBLUE='\033[1;34m'
LPURPLE='\033[1;35m'
LCYAN='\033[1;36m'
WHITE='\033[1;37m'
NC='\033[0m'
makefile()
{
BOARD="default"
PS3='Chose your board: '
options=("uno" "mega" "mega2560" "atmega8" "atmega168" "atmega328" "pro" "pro5v" "pro328" "pro5v328")
select opt in "${options[#]}"
do case $opt in
"uno") BOARD="uno"
cp -r /usr/lib/avrduino/data/boards_info/uno/board-info.h .
MCU="atmega328P"
F_CPU="16000000UL"
;;
"mega") BOARD="mega"
cp -r /usr/lib/avrduino/data/boards_info/mega/board-info.h .
F_CPU="16000000UL"
;;
"mega2560") BOARD="mega2560"
cp -r /usr/lib/avrduino/data/boards_info/mega2560/board-info.h .
F_CPU="16000000UL"
;;
"atmega8") BOARD="atmega8"
cp -r /usr/lib/avrduino/data/boards_info/atmega8/board_-nfo.h .
MCU="atmega8"
F_CPU="16000000UL"
;;
"atmega168") BOARD="atmega168"
cp -r /usr/lib/avrduino/data/boards_info/atmega168/board-info.h .
MCU="atmega168"
F_CPU="16000000UL"
;;
"atmega328") BOARD="atmega328"
cp -r /usr/lib/avrduino/data/boards_info/atmega328/board-info.h .
MCU="atmega328P"
F_CPU="16000000UL"
;;
"pro") BOARD="pro"
cp -r /usr/lib/avrduino/data/boards_info/pro/board-info.h .
MCU="unknow"
F_CPU="16000000UL"
;;
"pro5v") BOARD="pro5v"
cp -r /usr/lib/avrduino/data/boards_info/pro5v/board-info.h .
MCU="unknown"
F_CPU="16000000UL"
;;
"pro328") BOARD="pro328"
cp -r /usr/lib/avrduino/data/boards_info/pro328/board-info.h .
MCU="atmega328P"
F_CPU="16000000UL"
;;
"pro5v328") BOARD= "pro5v328"
cp -r /usr/lib/avrduino/data/boards_info/pro5v328/board-info.h .
MCU="atmega328P"
F_CPU="16000000UL"
;;
*)
echo "Error : Input is not valid"
echo "Exiting..."
return 1
;;
esac
break
done
[ -e Makefile ] && rm Makefile
read -p "Do you want to configure your Makefile settings [Y/n]: " CONFIGURE
if { [ "$CONFIGURE" == "Y" ] || [ "$CONFIGURE" == "y" ]; }; then
read -p "Enter your MCU: " MCU
read -p "Enter F_CPU: " F_CPU
fi
read -p "Enter ARDUINO_PORT: " ARDUINO_PORT
echo "ARDUINO_DIR = /usr/share/arduino">>Makefile
echo "BOARD_TAG = $BOARD">>Makefile
echo "ARDUINO_PORT = $ARDUINO_PORT">>Makefile
echo "NO_CORE = 1">>Makefile
echo "AVRDUDE_ARD_PROGRAMMER = arduino">>Makefile
echo "HEX_MAXIMUM_SIZE = 30720">>Makefile
echo "AVRDUDE_ARD_BAUDRATE = 115200">>Makefile
echo "#ISP_LOW_FUSE = 0xFF">>Makefile
echo "#ISP_HIGH_FUSE = 0xDA">>Makefile
echo "#ISP_EXT_FUSE = 0x05">>Makefile
echo "#ISP_LOCK_FUSE_PRE = 0x3F">>Makefile
echo "#ISP_LOCK_FUSE_POST = 0x0F">>Makefile
echo "MCU = $MCU">>Makefile
echo "F_CPU = $F_CPU">>Makefile
echo "VARIANT = standard">>Makefile
echo "ARDUINO_LIBS =">>Makefile
echo "include /usr/share/arduino/Arduino.mk">>Makefile
echo "$BOARD|$MCU|" >> .avrduino.txt
clear
echo -e "${LGREEN}Makefile settings${NC}"
echo -e "${LBLUE}ARDUINO_DIR = ${LRED}/usr/share/arduino ${NC}"
echo -e "${LBLUE}BOARD_TAG = ${LRED}$BOARD${NC}"
echo -e "${LBLUE}ARDUINO_PORT = ${LRED}$ARDUINO_PORT${NC}"
echo -e "${LBLUE}NO_CORE = ${LRED}1${NC}"
echo -e "${LBLUE}AVRDUDE_ARD_PROGRAMMER = ${LRED}arduino${NC}"
echo -e "${LBLUE}HEX_MAXIMUM_SIZE = ${LRED}30720${NC}"
echo -e "${LBLUE}AVRDUDE_ARD_BAUDRATE = ${LRED}115200${NC}"
echo -e "${DGRAY}#ISP_LOW_FUSE = ${RED}0xFF${NC}"
echo -e "${DGRAY}#ISP_HIGH_FUSE = ${RED}0xDA${NC}"
echo -e "${DGRAY}#ISP_EXT_FUSE = ${RED}0x05${NC}"
echo -e "${DGRAY}#ISP_LOCK_FUSE_PRE = ${RED}0x3F${NC}"
echo -e "${DGRAY}#ISP_LOCK_FUSE_POST = ${RED}0x0F${NC}"
echo -e "${LBLUE}MCU = ${LRED}$MCU${NC}"
echo -e "${LBLUE}F_CPU = ${LRED}$F_CPU${NC}"
echo -e "${LBLUE}VARIANT = ${LRED}standard${NC}"
echo -e "${LBLUE}ARDUINO_LIBS =${NC}"
}
initializeProject()
{
read -p "Project name: " PROJECT_NAME
if [ ! -e PROJECT_NAME ]; then
mkdir $PROJECT_NAME
cd $PROJECT_NAME
makefile #Call function that makes makefile
cp -r /usr/lib/avrduino/data/include/ .
echo -e "${LGREEN}Project created successfully ${NC}"
else
echo "AVRduino: Project with name [ $PROJECT_NAME ] already exists. "
echo "AVRduino: Stop project wizard and exit."
fi
}
clear
initializeProject
. doesn't execute the script as a process, it only loads it into your current shell process.
In that context, your "shebang" line, #!/bin/bash, is just a comment.
(You can put #! doodle poodle noodle there and it will run just as well.)
When you use system, it executes in /bin/sh, and thus your bash script has syntax errors.
One way to execute scripts is to make them executable:
chmod +x /usr/lib/avrduino/script/initialize.sh
and then you can just pass it directly to system:
system("/usr/lib/avrduino/script/initialize.sh");
Or, you could explictly execute it in bash:
system("/bin/bash /usr/lib/avrduino/script/initialize.sh");
OK, here's a way one might solve your "changing directory" problem:
Rewrite initialize.sh so it takes the project name as an argument instead of asking for it interactively (that's how normal Unix tools work, so stick with it).
Then add the following to your .bashrc:
make_project()
{
/usr/lib/avrduino/script/initialize.sh "$1" && cd "$1"
}
Then you can say make_project foo and get transported to the directory "foo".
Most likely it is the misplaced shebang causing a default shell to be run - make sure the shebang is at the beginning of the first line
#!/bin/bash
# rest of script
If that does not work change your system call to
system("/bin/bash /usr/lib/avrduino/script/initialize.sh");

Audit bash commands for bash RPG

I want to be able to write a program that when you type in commands, it will do things like count the amount of times you've used cd. Something similar to this:
[ : ~ $] cd public_html
Congratulations! You've earned the Badge 'cd master!'. Level up!
All my C++ file consists of so far is:
#include <iostream>
int main(int argc, char* argv[]) {
int counter = 0;
for (int i = 1; i < argc; i++) {
std::cout << argv[i] << std::endl;
if (argv[i] == "cd")
std::cout << "Badge earned 'cd master!' +5120 experience points" << std::endl;
}
return 0;
}
As it reflects one attempted solution involving:
#!/bin/sh
bash | tee ./main
and
bind 'RETURN: "echo $(!!) | tee ~/.main \n"'
I've decided to go with
export PROMPT_COMMAND='history | tail -n1'
But that would mean having to parse the output.
What's the easiest way of accomplishing this?
edit
Here's what I've managed to produce:
#!/bin/sh
export COUNTER=0
export MAXWIDTH=10
export TNL=1000
update_prompt() {
export PS1="> "
}
cd() {
COUNTER=$(($COUNTER + 25));
echo +25;
builtin cd $#;
}
help() {
echo "custom commands are: score";
}
score() {
echo $COUNTER"/"$TNL
BAR=$(yes "#" | head -n 10 | tr -d '\n')
OVERLAY=$(yes "%" | head -n 10 | tr -d '\n')
WIDTH=$(echo "$COUNTER*$MAXWIDTH/$TNL" | bc)
FIRST=${BAR:0:WIDTH}
SECOND=${OVERLAY:0:$((MAXWIDTH-WIDTH))}
echo "["$FIRST$SECOND"]"
}
exit() {
echo "Bye bye";
builtin exit $#;
}
export -f update_prompt
export -f cd # export the function
export -f help
export -f score
export -f exit
bash # run subshell with the exported functions
update_prompt
An easy solution is to overwrite the cd command of your shell inside the shell itself. For example, in Bash or ZSH:
cd() {
echo "Congratulations";
builtin cd $#;
}
(This is for example used in projects like autoenv.)
You can do the same for all other commands. You can also call your C++ code from there.
If you want to put that into a script, e.g. name it learn-bash.sh:
cd() { ... }
export -f cd # export the function
bash # run subshell with the exported functions
Another solution, where you have much more power, but which is way more involved: take the source code of Bash (it's C) and extend it (by C or C++). Then you can basically do whatever you want. And you have everything directly there, i.e. the parsed commands, etc.
After every command COMMAND_PROMPT is executed within bash. You could use that with history to see the last command used.
You can read here on how PS1, PS2, PS3 and COMMAND_PROMPT work in bash.
There are a few answers on exactly this question already on SO:
How can I intercept commands that contain a certain string?
bash: how to intercept every command
bash: How to intercept command line and do various actions based on the contents?
I've done something similar a while ago, and here's the solution I've found.
You want to add the following lines to .bashrc:
hook() {
whatever "$#"
}
invoke_hook() {
[ -n "$COMP_LINE" ] && return
[ "$BASH_COMMAND" = "$PROMPT_COMMAND" ] && return
local command=`history 1 | sed -e "s/^[ ]*[0-9]*[ ]*//g"`;
hook "$command"
}
trap 'invoke_hook' DEBUG
Replace whatever with your C++ program. This will execute your hook before each command, and will pass the original command as the arguments.

process text file in ksh append data

Following doesn't work.
I need to add a , and an input param at the end of the script. Please help
#!/bin/ksh
data_log="/usr/data/data_log.dbg"
err_file="/usr/data/data_log.err"
if [ $# -eq 1 ]; then
inParam=$1
fi
processInfo ${inParam} > ${data_log}
#Append ,inParam to each line in log for further processing
for logger in `cat ${data_log}`
{
echo ${logger} | sed s/$/,${inParam}/ >> ${err_file}
}
rm -rf ${data_log}
Replace the for logger in loop where you're reading the file with this:
cat ${data_log} | while read line
do
echo "${line},${inParam}" >> ${err_file}
done
...which I think can be written like this (no shell to test with at the moment) to avoid a UUOC...
while read line
do
echo "${line},${inParam}" >> ${err_file}
done < ${data_log}