I have a shell that runs where the preset env variables include:
FOOCOUNT=4
FOO_0=John
FOO_1=Barry
FOO_2=Lenny
FOO_3=Samuel
I can not change the way I get this data.
I want to run a loop that generates up the variable and uses the contents.
echo "Hello $FOO_count"
This syntax is however wrong and that is what I am searching for...
count=$FOOCOUNT
counter=0
while [ $counter -lt $count ]
do
#I am looking for the syntax for: <<myContructedVar= $ + 'FOO_' + $counter>>
counter=`expr $counter + 1`
echo "Greeting #$counter: Hello, ${myContructedVar}."
done
Thanks very much
The key is eval:
count=$FOOCOUNT
counter=0
while [ $counter -lt $count ]
do
myConstructedVar=FOO_$counter
counter=`expr $counter + 1`
echo "Greeting #$counter: Hello, `eval echo \$${myConstructedVar}`."
done
The loop arithmetic is old school - the way I write the code. Modern shells have more arithmetic built in - but the question is tagged Bourne shell.
You'll need an eval and a deferred sigil:
$ foo_0=john
$ count=0
$ name="\$foo_$count"
$ echo $name
$foo_0
$ eval echo "$name"
john
but unless the index is truly important to you, you might use
for i in "$foo_0" "$foo_1" "$foo_2" ... ; do
...
done
and get rid of the badly named pseudo-array. And, if you have an upper bound on the number of the number of foo_x and there are no special characters in the various foos (in particular no character in $IFS which defaults to <space><tab><return>) then you can use the null-argument collapsing feature of the shell and:
$ for i in $foo_0 $foo_1 $foo_2 ; do
> echo '***' $i
> done
*** john
and allow the shell to ignore unset foo_x
It's been a very long time since I've done any Bourne shell but have you tried the eval command?
Related
I am confused by the usage of brackets, parentheses, curly braces in Bash, as well as the difference between their double or single forms. Is there a clear explanation?
In Bash, test and [ are shell builtins.
The double bracket, which is a shell keyword, enables additional functionality. For example, you can use && and || instead of -a and -o and there's a regular expression matching operator =~.
Also, in a simple test, double square brackets seem to evaluate quite a lot quicker than single ones.
$ time for ((i=0; i<10000000; i++)); do [[ "$i" = 1000 ]]; done
real 0m24.548s
user 0m24.337s
sys 0m0.036s
$ time for ((i=0; i<10000000; i++)); do [ "$i" = 1000 ]; done
real 0m33.478s
user 0m33.478s
sys 0m0.000s
The braces, in addition to delimiting a variable name are used for parameter expansion so you can do things like:
Truncate the contents of a variable
$ var="abcde"; echo ${var%d*}
abc
Make substitutions similar to sed
$ var="abcde"; echo ${var/de/12}
abc12
Use a default value
$ default="hello"; unset var; echo ${var:-$default}
hello
and several more
Also, brace expansions create lists of strings which are typically iterated over in loops:
$ echo f{oo,ee,a}d
food feed fad
$ mv error.log{,.OLD}
(error.log is renamed to error.log.OLD because the brace expression
expands to "mv error.log error.log.OLD")
$ for num in {000..2}; do echo "$num"; done
000
001
002
$ echo {00..8..2}
00 02 04 06 08
$ echo {D..T..4}
D H L P T
Note that the leading zero and increment features weren't available before Bash 4.
Thanks to gboffi for reminding me about brace expansions.
Double parentheses are used for arithmetic operations:
((a++))
((meaning = 42))
for ((i=0; i<10; i++))
echo $((a + b + (14 * c)))
and they enable you to omit the dollar signs on integer and array variables and include spaces around operators for readability.
Single brackets are also used for array indices:
array[4]="hello"
element=${array[index]}
Curly brace are required for (most/all?) array references on the right hand side.
ephemient's comment reminded me that parentheses are also used for subshells. And that they are used to create arrays.
array=(1 2 3)
echo ${array[1]}
2
A single bracket ([) usually actually calls a program named [; man test or man [ for more info. Example:
$ VARIABLE=abcdef
$ if [ $VARIABLE == abcdef ] ; then echo yes ; else echo no ; fi
yes
The double bracket ([[) does the same thing (basically) as a single bracket, but is a bash builtin.
$ VARIABLE=abcdef
$ if [[ $VARIABLE == 123456 ]] ; then echo yes ; else echo no ; fi
no
Parentheses (()) are used to create a subshell. For example:
$ pwd
/home/user
$ (cd /tmp; pwd)
/tmp
$ pwd
/home/user
As you can see, the subshell allowed you to perform operations without affecting the environment of the current shell.
(a) Braces ({}) are used to unambiguously identify variables. Example:
$ VARIABLE=abcdef
$ echo Variable: $VARIABLE
Variable: abcdef
$ echo Variable: $VARIABLE123456
Variable:
$ echo Variable: ${VARIABLE}123456
Variable: abcdef123456
(b) Braces are also used to execute a sequence of commands in the current shell context, e.g.
$ { date; top -b -n1 | head ; } >logfile
# 'date' and 'top' output are concatenated,
# could be useful sometimes to hunt for a top loader )
$ { date; make 2>&1; date; } | tee logfile
# now we can calculate the duration of a build from the logfile
There is a subtle syntactic difference with ( ), though (see bash reference) ; essentially, a semicolon ; after the last command within braces is a must, and the braces {, } must be surrounded by spaces.
Brackets
if [ CONDITION ] Test construct
if [[ CONDITION ]] Extended test construct
Array[1]=element1 Array initialization
[a-z] Range of characters within a Regular Expression
$[ expression ] A non-standard & obsolete version of $(( expression )) [1]
[1] http://wiki.bash-hackers.org/scripting/obsolete
Curly Braces
${variable} Parameter substitution
${!variable} Indirect variable reference
{ command1; command2; . . . commandN; } Block of code
{string1,string2,string3,...} Brace expansion
{a..z} Extended brace expansion
{} Text replacement, after find and xargs
Parentheses
( command1; command2 ) Command group executed within a subshell
Array=(element1 element2 element3) Array initialization
result=$(COMMAND) Command substitution, new style
>(COMMAND) Process substitution
<(COMMAND) Process substitution
Double Parentheses
(( var = 78 )) Integer arithmetic
var=$(( 20 + 5 )) Integer arithmetic, with variable assignment
(( var++ )) C-style variable increment
(( var-- )) C-style variable decrement
(( var0 = var1<98?9:21 )) C-style ternary operation
I just wanted to add these from TLDP:
~:$ echo $SHELL
/bin/bash
~:$ echo ${#SHELL}
9
~:$ ARRAY=(one two three)
~:$ echo ${#ARRAY}
3
~:$ echo ${TEST:-test}
test
~:$ echo $TEST
~:$ export TEST=a_string
~:$ echo ${TEST:-test}
a_string
~:$ echo ${TEST2:-$TEST}
a_string
~:$ echo $TEST2
~:$ echo ${TEST2:=$TEST}
a_string
~:$ echo $TEST2
a_string
~:$ export STRING="thisisaverylongname"
~:$ echo ${STRING:4}
isaverylongname
~:$ echo ${STRING:6:5}
avery
~:$ echo ${ARRAY[*]}
one two one three one four
~:$ echo ${ARRAY[*]#one}
two three four
~:$ echo ${ARRAY[*]#t}
one wo one hree one four
~:$ echo ${ARRAY[*]#t*}
one wo one hree one four
~:$ echo ${ARRAY[*]##t*}
one one one four
~:$ echo $STRING
thisisaverylongname
~:$ echo ${STRING%name}
thisisaverylong
~:$ echo ${STRING/name/string}
thisisaverylongstring
The difference between test, [ and [[ is explained in great details in the BashFAQ.
(Note: The link shows many examples for comparison)
To cut a long story short: test implements the old, portable syntax of
the command. In almost all shells (the oldest Bourne shells are the
exception), [ is a synonym for test (but requires a final argument of
]). Although all modern shells have built-in implementations of [,
there usually still is an external executable of that name, e.g.
/bin/[.
[[ is a new, improved version of it, and it is a keyword, not a program.
This has beneficial effects on the ease of use, as shown below. [[ is
understood by KornShell and BASH (e.g. 2.03), but not by the older
POSIX or BourneShell.
And the conclusion:
When should the new test command [[ be used, and when the old one [?
If portability/conformance to POSIX or the BourneShell is a concern, the old syntax should
be used. If on the other hand the script requires BASH, Zsh, or KornShell,
the new syntax is usually more flexible.
Parentheses in function definition
Parentheses () are being used in function definition:
function_name () { command1 ; command2 ; }
That is the reason you have to escape parentheses even in command parameters:
$ echo (
bash: syntax error near unexpected token `newline'
$ echo \(
(
$ echo () { command echo The command echo was redefined. ; }
$ echo anything
The command echo was redefined.
Some common and handy uses for brackets, parenthesis, and braces
As mentioned above, sometimes you want a message displayed without losing the return value. This is a handy snippet:
$ [ -f go.mod ] || { echo 'File not found' && false; }
This produced no output and a 0 (true) return value if the file go.mod exists in the current directory. Test the result:
$ echo $?
0
If the file does not exist, you get the message but also a return value of 1 (false), which can also be tested:
$ [ -f fake_file ] || { echo 'File not found'; false; }
File not found
$ echo $?
1
You can also simply create a function to check if a file exists:
fileexists() { [ -f "$1" ]; }
or if a file is readable (not corrupted, have permissions, etc.):
canread() { [ -r "$1" ]; }
or if it is a directory:
isdir() { [ -d "$1" ]; }
or is writable for the current user:
canwrite() { [ -w "$1" ]; }
or if a file exists and is not empty (like a log file with content...)
isempty() { [ -s "$1" ]; }
There are more details at: TLDP
You can also see if a program exists and is available on the path:
exists () { command -v $1 > /dev/null 2>&1; }
This is useful in scripts, for example:
# gitit does an autosave commit to the current
# if Git is installed and available.
# If git is not available, it will use brew
# (on macOS) to install it.
#
# The first argument passed, if any, is used as
# the commit message; otherwise the default is used.
gitit() {
$(exists git) && {
git add --all;
git commit -m "${1:-'GitBot: dev progress autosave'}";
git push;
} || brew install git;
}
Additional info about How to use parentheses to group and expand expressions:
(it is listed on the link syntax-brackets)
Some main points in there:
Group commands in a sub-shell: ( )
(list)
Group commands in the current shell: { }
{ list; }
Test - return the binary result of an expression: [[ ]]
[[ expression ]]
Arithmetic expansion
The format for Arithmetic expansion is:
$(( expression ))
The format for a simple Arithmetic Evaluation is:
(( expression ))
Combine multiple expressions
( expression )
(( expr1 && expr2 ))
Truncate the contents of a variable
$ var="abcde"; echo ${var%d*}
abc
Make substitutions similar to sed
$ var="abcde"; echo ${var/de/12}
abc12
Use a default value
$ default="hello"; unset var; echo ${var:-$default}
hello
Please tell me what is wrong with the UNIX code below.
#!/bin/ksh
p=10
for i in $p
do
echo $i
done
i am expecting output as
1
2
3
.
.
.
but the output am getting is just 10
I need for loop not while loop.
in ksh
#!/bin/ksh
p=10
i=1
while ((i<=p)); do
echo $i
i=$((i+1))
done
or
#!/bin/ksh
# with for you can only do this
for i in 1 2 3 4 5 6 7 8 9 10; do
echo $i
done
in bash it works as expected
#!/bin/bash
p=10
for (( i=1; i<=p; i++ )); do
echo $i
done
there is a Linux command seqthat can be used for both ksh and bash. But it is a Linux command. So this will not work on Solaris or other Unix systems that don't have the progrtam seq installed.
# on Linux, bash or ksh
p=10
for i in $(seq $p); do
echo $i
done
The following uses only shell built-ins and therefore will work for all bash installations (e.g. on Solaris) but not for ksh
#!/bin/bash
p=10
for i in `eval echo {1..$p}`; do
echo $i
done
This complicated construct is necessary because of brace expansion occurrs before variable expansion
You have to assign a range. Otherwise the loop can't work. This should do it:
#!/bin/ksh
p=10
for i in {0..$p}
do
echo $i
done
#fedorqui: You are right, I absolutely missed that. When I do stuff like this in Bash (I don't know if it's the same for KornShell), I go like:
for ((i=0; i<$p; i++))
in UNIX KSH
#!/bin/ksh
while [ ${i:=1} -le 10 ]
do
echo "$i"
let i+=1
done
Why the output is {1..3} rather than 123 ?
#!/bin/sh
a=1
for i in {$a..3}
do
echo -n $i
done
If I change {$a..3} to $(echo {$a..3}), it does not work either.
Brace expansion is performed before parameter substitution. But since that isn't a valid brace expansion, it isn't expanded. Use seq instead.
Ignacio's answer is right.
Here are some other solutions!
You can use a c-style for-loop in bash:
for (( i=a; i<=3; i++ ))
Or you can use dangerous eval, but you have to be sure that $a variable can't be anything else but a number, especially if the user is able to change it:
for i in $(echo eval {$a..3})
Or while loop with a variable in pure sh:
i=$a
while [ "$i" -le 3 ]
do
echo -n $i
i=$(( i + 1 ))
done
I have a environment config file where i have defined the environment variables. I use source to get these variables inside my shell script(bash).
I use a checkout command in my shell script which checks out the files from location defined in an environment variable. Now i need to use multiple locations to checkout the files which can be any number for different run of shell script.
For eg. User gives two paths, PATH1 and PATH2 in config file and a NUM_OF_PATHS as 2.
In my shell script I want to do something like below for using path.
i=0
echo ${NUM_OF_PATHS}
while [ $i -lt ${NUM_OF_PATHS} ]
do
checkout $PATH{$i}
i=`expr $i + 1`
done
How can I use the variable i to form an environment variable PATH1 or PATH2 etc.?
i=1
while [ $i -le ${NUM_OF_PATHS} ]
do
CPATH=$(eval echo \$\{PATH$i\})
echo "PATH$i: $CPATH"
let i++
done
eval combines and evaluates its parameters and executes the combined expression. Here, eval executes: echo ${PATH1}. In order to do this, we first escape the ${...} so that echo can receive them after eval. The only un-escaped special character is $ before i. eval expands this and strips off the escaped characters and executes echo with the result.
So, CPATH=$(eval echo \$\{PATH$i\}) becomes CPATH=$(echo ${PATH1}) and CPATH gets the echo output.
Here is a complete example that I think will do what you want. Below is my original message that was voted down for a reason I don't completely understand:
$ cat test.sh
function checkout() {
echo "Registering $1"
}
PATH1="Path1;/usr/bin"
PATH2="Path2;/bin"
NUM_OF_PATHS=2
i=1
echo $NUM_OF_PATHS
while [ $i -le $NUM_OF_PATHS ]
do
eval "checkout \$PATH$i"
i=`expr $i + 1`
done
$ bash test.sh
2
Registering Path1;/usr/bin
Registering Path2;/bin
$
Original Message
You can use the "eval" command. Here is an example (works on GNU bash, version 4.2.37(2)-release):
$ A1="Variable 1"
$ A2="Variable 2"
$ for i in {1..2}; do eval "echo \$A$i"; done
Variable 1
Variable 2
$
The string will evaluate to "echo $A1" and "echo $A2", and then eval will do what you want.
Why don't you use array variable? Use one array MYPATH[] instead multi PATH1 PATH2 variables
MYPATH=(
path0
path1
path2
)
MYPATH[3]=path3
NUM_OF_PATHS="${#MYPATH[#]}"
echo ${NUM_OF_PATHS}
for ((i=0; i < NUM_OF_PATHS; i++))
do
checkout ${MYPATH[$i]}
done
Use curly braces around the name: ${PATH$i}
I have a bash script that is being used in a CGI. The CGI sets the $QUERY_STRING environment variable by reading everything after the ? in the URL. For example, http://example.com?a=123&b=456&c=ok sets QUERY_STRING=a=123&b=456&c=ok.
Somewhere I found the following ugliness:
b=$(echo "$QUERY_STRING" | sed -n 's/^.*b=\([^&]*\).*$/\1/p' | sed "s/%20/ /g")
which will set $b to whatever was found in $QUERY_STRING for b. However, my script has grown to have over ten input parameters. Is there an easier way to automatically convert the parameters in $QUERY_STRING into environment variables usable by bash?
Maybe I'll just use a for loop of some sort, but it'd be even better if the script was smart enough to automatically detect each parameter and maybe build an array that looks something like this:
${parm[a]}=123
${parm[b]}=456
${parm[c]}=ok
How could I write code to do that?
Try this:
saveIFS=$IFS
IFS='=&'
parm=($QUERY_STRING)
IFS=$saveIFS
Now you have this:
parm[0]=a
parm[1]=123
parm[2]=b
parm[3]=456
parm[4]=c
parm[5]=ok
In Bash 4, which has associative arrays, you can do this (using the array created above):
declare -A array
for ((i=0; i<${#parm[#]}; i+=2))
do
array[${parm[i]}]=${parm[i+1]}
done
which will give you this:
array[a]=123
array[b]=456
array[c]=ok
Edit:
To use indirection in Bash 2 and later (using the parm array created above):
for ((i=0; i<${#parm[#]}; i+=2))
do
declare var_${parm[i]}=${parm[i+1]}
done
Then you will have:
var_a=123
var_b=456
var_c=ok
You can access these directly:
echo $var_a
or indirectly:
for p in a b c
do
name="var$p"
echo ${!name}
done
If possible, it's better to avoid indirection since it can make code messy and be a source of bugs.
you can break $QUERY down using IFS. For example, setting it to &
$ QUERY="a=123&b=456&c=ok"
$ echo $QUERY
a=123&b=456&c=ok
$ IFS="&"
$ set -- $QUERY
$ echo $1
a=123
$ echo $2
b=456
$ echo $3
c=ok
$ array=($#)
$ for i in "${array[#]}"; do IFS="=" ; set -- $i; echo $1 $2; done
a 123
b 456
c ok
And you can save to a hash/dictionary in Bash 4+
$ declare -A hash
$ for i in "${array[#]}"; do IFS="=" ; set -- $i; hash[$1]=$2; done
$ echo ${hash["b"]}
456
Please don't use the evil eval junk.
Here's how you can reliably parse the string and get an associative array:
declare -A param
while IFS='=' read -r -d '&' key value && [[ -n "$key" ]]; do
param["$key"]=$value
done <<<"${QUERY_STRING}&"
If you don't like the key check, you could do this instead:
declare -A param
while IFS='=' read -r -d '&' key value; do
param["$key"]=$value
done <<<"${QUERY_STRING:+"${QUERY_STRING}&"}"
Listing all the keys and values from the array:
for key in "${!param[#]}"; do
echo "$key: ${param[$key]}"
done
I packaged the sed command up into another script:
$cat getvar.sh
s='s/^.*'${1}'=\([^&]*\).*$/\1/p'
echo $QUERY_STRING | sed -n $s | sed "s/%20/ /g"
and I call it from my main cgi as:
id=`./getvar.sh id`
ds=`./getvar.sh ds`
dt=`./getvar.sh dt`
...etc, etc - you get idea.
works for me even with a very basic busybox appliance (my PVR in this case).
To converts the contents of QUERY_STRING into bash variables use the following command:
eval $(echo ${QUERY_STRING//&/;})
The inner step, echo ${QUERY_STRING//&/;}, substitutes all ampersands with semicolons producing a=123;b=456;c=ok which the eval then evaluates into the current shell.
The result can then be used as bash variables.
echo $a
echo $b
echo $c
The assumptions are:
values will never contain '&'
values will never contain ';'
QUERY_STRING will never contain malicious code
While the accepted answer is probably the most beautiful one, there might be cases where security is super-important, and it needs to be also well-visible from your script.
In such a case, first I wouldn't use bash for the task, but if it should be done on some reason, it might be better to avoid these new array - dictionary features, because you can't be sure, how exactly are they escaped.
In this case, the good old primitive solutions might work:
QS="${QUERY_STRING}"
while [ "${QS}" != "" ]
do
nameval="${QS%%&*}"
QS="${QS#$nameval}"
QS="${QS#&}"
name="${nameval%%=*}"
val="${nameval#$name}"
val="${nameval#=}"
# and here we have $name and $val as names and values
# ...
done
This iterates on the name-value pairs of the QUERY_STRING, and there is no way to circumvent it with any tricky escape sequence - the " is a very strong thing in bash, except a single variable name substitution, which is fully controlled by us, nothing can be tricked.
Furthermore, you can inject your own processing code into "# ...". This enables you to allow only your own, well-defined (and, ideally, short) list of the allowed variable names. Needless to say, LD_PRELOAD shouldn't be one of them. ;-)
Furthermore, no variable will be exported, and exclusively QS, nameval, name and val is used.
Following the correct answer, I've done myself some changes to support array variables like in this other question. I added also a decode function of which I can not find the author to give some credit.
Code appears somewhat messy, but it works. Changes and other recommendations would be greatly appreciated.
function cgi_decodevar() {
[ $# -ne 1 ] && return
local v t h
# replace all + with whitespace and append %%
t="${1//+/ }%%"
while [ ${#t} -gt 0 -a "${t}" != "%" ]; do
v="${v}${t%%\%*}" # digest up to the first %
t="${t#*%}" # remove digested part
# decode if there is anything to decode and if not at end of string
if [ ${#t} -gt 0 -a "${t}" != "%" ]; then
h=${t:0:2} # save first two chars
t="${t:2}" # remove these
v="${v}"`echo -e \\\\x${h}` # convert hex to special char
fi
done
# return decoded string
echo "${v}"
return
}
saveIFS=$IFS
IFS='=&'
VARS=($QUERY_STRING)
IFS=$saveIFS
for ((i=0; i<${#VARS[#]}; i+=2))
do
curr="$(cgi_decodevar ${VARS[i]})"
next="$(cgi_decodevar ${VARS[i+2]})"
prev="$(cgi_decodevar ${VARS[i-2]})"
value="$(cgi_decodevar ${VARS[i+1]})"
array=${curr%"[]"}
if [ "$curr" == "$next" ] && [ "$curr" != "$prev" ] ;then
j=0
declare var_${array}[$j]="$value"
elif [ $i -gt 1 ] && [ "$curr" == "$prev" ]; then
j=$((j + 1))
declare var_${array}[$j]="$value"
else
declare var_$curr="$value"
fi
done
I would simply replace the & to ;. It will become to something like:
a=123;b=456;c=ok
So now you need just evaluate and read your vars:
eval `echo "${QUERY_STRING}"|tr '&' ';'`
echo $a
echo $b
echo $c
A nice way to handle CGI query strings is to use Haserl which acts as a wrapper around your Bash cgi script, and offers convenient and secure query string parsing.
To bring this up to date, if you have a recent Bash version then you can achieve this with regular expressions:
q="$QUERY_STRING"
re1='^(\w+=\w+)&?'
re2='^(\w+)=(\w+)$'
declare -A params
while [[ $q =~ $re1 ]]; do
q=${q##*${BASH_REMATCH[0]}}
[[ ${BASH_REMATCH[1]} =~ $re2 ]] && params+=([${BASH_REMATCH[1]}]=${BASH_REMATCH[2]})
done
If you don't want to use associative arrays then just change the penultimate line to do what you want. For each iteration of the loop the parameter is in ${BASH_REMATCH[1]} and its value is in ${BASH_REMATCH[2]}.
Here is the same thing as a function in a short test script that iterates over the array outputs the query string's parameters and their values
#!/bin/bash
QUERY_STRING='foo=hello&bar=there&baz=freddy'
get_query_string() {
local q="$QUERY_STRING"
local re1='^(\w+=\w+)&?'
local re2='^(\w+)=(\w+)$'
while [[ $q =~ $re1 ]]; do
q=${q##*${BASH_REMATCH[0]}}
[[ ${BASH_REMATCH[1]} =~ $re2 ]] && eval "$1+=([${BASH_REMATCH[1]}]=${BASH_REMATCH[2]})"
done
}
declare -A params
get_query_string params
for k in "${!params[#]}"
do
v="${params[$k]}"
echo "$k : $v"
done
Note the parameters end up in the array in reverse order (it's associative so that shouldn't matter).
why not this
$ echo "${QUERY_STRING}"
name=carlo&last=lanza&city=pfungen-CH
$ saveIFS=$IFS
$ IFS='&'
$ eval $QUERY_STRING
$ IFS=$saveIFS
now you have this
name = carlo
last = lanza
city = pfungen-CH
$ echo "name is ${name}"
name is carlo
$ echo "last is ${last}"
last is lanza
$ echo "city is ${city}"
city is pfungen-CH
#giacecco
To include a hiphen in the regex you could change the two lines as such in answer from #starfry.
Change these two lines:
local re1='^(\w+=\w+)&?'
local re2='^(\w+)=(\w+)$'
To these two lines:
local re1='^(\w+=(\w+|-|)+)&?'
local re2='^(\w+)=((\w+|-|)+)$'
For all those who couldn't get it working with the posted answers (like me),
this guy figured it out.
Can't upvote his post unfortunately...
Let me repost the code here real quick:
#!/bin/sh
if [ "$REQUEST_METHOD" = "POST" ]; then
if [ "$CONTENT_LENGTH" -gt 0 ]; then
read -n $CONTENT_LENGTH POST_DATA <&0
fi
fi
#echo "$POST_DATA" > data.bin
IFS='=&'
set -- $POST_DATA
#2- Value1
#4- Value2
#6- Value3
#8- Value4
echo $2 $4 $6 $8
echo "Content-type: text/html"
echo ""
echo "<html><head><title>Saved</title></head><body>"
echo "Data received: $POST_DATA"
echo "</body></html>"
Hope this is of help for anybody.
Cheers
Actually I liked bolt's answer, so I made a version which works with Busybox as well (ash in Busybox does not support here string).
This code will accept key1 and key2 parameters, all others will be ignored.
while IFS= read -r -d '&' KEYVAL && [[ -n "$KEYVAL" ]]; do
case ${KEYVAL%=*} in
key1) KEY1=${KEYVAL#*=} ;;
key2) KEY2=${KEYVAL#*=} ;;
esac
done <<END
$(echo "${QUERY_STRING}&")
END
One can use the bash-cgi.sh, which processes :
the query string into the $QUERY_STRING_GET key and value array;
the post request data (x-www-form-urlencoded) into the $QUERY_STRING_POST key and value array;
the cookies data into the $HTTP_COOKIES key and value array.
Demands bash version 4.0 or higher (to define the key and value arrays above).
All processing is made by bash only (i.e. in an one process) without any external dependencies and additional processes invoking.
It has:
the check for max length of data, which can be transferred to it's input,
as well as processed as query string and cookies;
the redirect() procedure to produce redirect to itself with the extension changed to .html (it is useful for an one page's sites);
the http_header_tail() procedure to output the last two strings of the HTTP(S) respond's header;
the $REMOTE_ADDR value sanitizer from possible injections;
the parser and evaluator of the escaped UTF-8 symbols embedded into the values passed to the $QUERY_STRING_GET, $QUERY_STRING_POST and $HTTP_COOKIES;
the sanitizer of the $QUERY_STRING_GET, $QUERY_STRING_POST and $HTTP_COOKIES values against possible SQL injections (the escaping like the mysql_real_escape_string php function does, plus the escaping of # and $).
It is available here:
https://github.com/VladimirBelousov/fancy_scripts
This works in dash using for in loop
IFS='&'
for f in $query_string; do
value=${f##*=}
key=${f%%=*}
# if you need environment variable -> eval "qs_$key=$value"
done