How to fix the following code so that it can store the result of sed, which will replace the _
with -?
My code:
names=()
for entry_ in $foo
do
names+=($entry_ | sed -e "s/_/-/g")
done
echo names
You don't need sed for this, you can use bash's built-in parameter expansion + substitution capability to replace all _ characters with -: ${var//_/-}. You can even use it to do this for the entire list of elements in a single operation, but how you do it depends on what the source variable, foo, actually is.
If foo is an array (the much better way to do things), you can combine [#] ("get me all elements of the array") with the substitution:
names=( "${foo[#]//_/-}" )
If foo is a plain string, and you need to use word splitting to break it into elements for the array, you can do essentially the same thing without the [#] ('cause it's not an array) or the double-quotes (which prevent word splitting):
names=( ${foo//_/-} )
Note: I recommend avoiding word splitting if possible -- it often does something close to what you want, but almost never exactly what you want.
P.s. I third the recommendation of shellcheck. Among other things, it'll flag anything involving word splitting as a probable mistake.
This should be enough to get you there.
names=()
names+=$(echo "hello_world" | sed -e "s/_/-/g")
echo $names
Note that you need $ before echoing your variable.
Also. Look into installing shellcheck for your code editor and it will help you catch sneaky bugs and build better shell programming practices.
The $# variable seems to maintain quoting around its arguments so that, for example:
$ function foo { for i in "$#"; do echo $i; done }
$ foo herp "hello world" derp
herp
hello world
derp
I am also aware that bash arrays, work the same way:
$ a=(herp "hello world" derp)
$ for i in "${a[#]}"; do echo $i; done
herp
hello world
derp
What is actually going on with variables like this? Particularly when I add something to the quote like "duck ${a[#]} goose". If its not space separated what is it?
Usually, double quotation marks in Bash mean "make everything between the quotation marks one word, even if it has separators in it." But as you've noticed, $# behaves differently when it's within double quotes. This is actually a parsing hack that dates back to Bash's predecessor, the Bourne shell, and this special behavior applies only to this particular variable.
Without this hack (I use the term because it seems inconsistent from a language perspective, although it's very useful), it would be difficult for a shell script to pass along its array of arguments to some other command that wants the same arguments. Some of those arguments might have spaces in them, but how would it pass them to another command without the shell either lumping them together as one big word or reparsing the list and splitting the arguments that have whitespace?
Well, you could pass an array of arguments, and the Bourne shell really only has one array, represented by $* or $#, whose number of elements is $# and whose elements are $1, $2, etc, the so-called positional parameters.
An example. Suppose you have three files in the current directory, named aaa, bbb, and cc c (the third file has a space in the name). You can initialize the array (that is, you can set the positional parameters) to be the names of the files in the current directory like this:
set -- *
Now the array of positional parameters holds the names of the files. $#, the number of elements, is three:
$ echo $#
3
And we can iterate over the position parameters in a few different ways.
1) We can use $*:
$ for file in $*; do
> echo "$file"
> done
but that re-separates the arguments on whitespace and calls echo four times:
aaa
bbb
cc
c
2) Or we could put quotation marks around $*:
$ for file in "$*"; do
> echo "$file"
> done
but that groups the whole array into one argument and calls echo just once:
aaa bbb cc c
3) Or we could use $# which represents the same array but behaves differently in double quotes:
$ for file in "$#"; do
> echo "$file"
> done
will produce
aaa
bbb
cc c
because $1 = "aaa", $2 = "bbb", and $3 = "cc c" and "$#" leaves the elements intact. If you leave off the quotation marks around $#, the shell will flatten and re-parse the array, echo will be called four times, and you'll get the same thing you got with a bare $*.
This is especially useful in a shell script, where the positional parameters are the arguments that were passed to your script. To pass those same arguments to some other command -- without the shell resplitting them on whitespace -- use "$#".
# Truncate the files specified by the args
rm "$#"
touch "$#"
In Bourne, this behavior only applies to the positional parameters because it's really the only array supported by the language. But you can create other arrays in Bash, and you can even apply the old parsing hack to those arrays using the special "${ARRAYNAME[#]}" syntax, whose at-sign feels almost like a wink to Mr. Bourne:
$ declare -a myarray
$ myarray[0]=alpha
$ myarray[1]=bravo
$ myarray[2]="char lie"
$ for file in "${myarray[#]}"; do echo "$file"; done
alpha
bravo
char lie
Oh, and about your last example, what should the shell do with "pre $# post" where you have $# within double quotes but you have other stuff in there, too? Recent versions of Bash preserve the array, prepend the text before the $# to the first array element, and append the text after the $# to the last element:
pre aaa
bb
cc c post
I'm writing a Terminal Match-Anything Pattern Rule, i.e. %::, that, as expected, will run only if no other target is matched. In its recipe I want to iterate over makefile's explicit targets and check if the found pattern ($*) is the beginning of any other target
By now I'm successfully getting all desired targets in a space-separated string and storing it in a variable TARGETS, however I couldn't turn it in an array to be able to iterate over each word in the string.
For instance
%::
$(eval TARGETS ::= $(shell grep -Ph "^[^\t].*::.*##" ./Makefile | cut -d : -f 1 | sort))
echo $(TARGETS)
gives me just what I was expecting:
build clean compile deploy execute init run serve
The Question
How could I iterate over each of $(TARGET) string words inside a GNU Make 4.2.1 loop?
I found a bunch of BASH solutions, but none of them worked in my tests:
Reading a delimited string into an array in Bash
How to split one string into multiple strings separated by at least >one space in bash shell?
It's generally a really bad idea to use eval and shell inside a recipe. A recipe is already a shell script so you should just use shell scripting.
It's not really clear exactly what you want to do. If you want to do this in a recipe, you can use a shell loop:
%::
TARGETS=$$(grep -Ph "^[^\t].*::.*##" ./Makefile | cut -d : -f 1 | sort); \
for t in $$TARGETS; do \
echo $$t; \
done
If you want to do it outside of a recipe you can use the GNU make foreach function.
I can not export an array from a bash script to another bash script like this:
export myArray[0]="Hello"
export myArray[1]="World"
When I write like this there are no problem:
export myArray=("Hello" "World")
For several reasons I need to initialize my array into multiple lines. Do you have any solution?
Array variables may not (yet) be exported.
From the manpage of bash version 4.1.5 under ubuntu 10.04.
The following statement from Chet Ramey (current bash maintainer as of 2011) is probably the most official documentation about this "bug":
There isn't really a good way to encode an array variable into the environment.
http://www.mail-archive.com/bug-bash#gnu.org/msg01774.html
TL;DR: exportable arrays are not directly supported up to and including bash-5.1, but you can (effectively) export arrays in one of two ways:
a simple modification to the way the child scripts are invoked
use an exported function to store the array initialisation, with a simple modification to the child scripts
Or, you can wait until bash-4.3 is released (in development/RC state as of February 2014, see ARRAY_EXPORT in the Changelog). Update: This feature is not enabled in 4.3. If you define ARRAY_EXPORT when building, the build will fail. The author has stated it is not planned to complete this feature.
The first thing to understand is that the bash environment (more properly command execution environment) is different to the POSIX concept of an environment. The POSIX environment is a collection of un-typed name=value pairs, and can be passed from a process to its children in various ways (effectively a limited form of IPC).
The bash execution environment is effectively a superset of this, with typed variables, read-only and exportable flags, arrays, functions and more. This partly explains why the output of set (bash builtin) and env or printenv differ.
When you invoke another bash shell you're starting a new process, you loose some bash state. However, if you dot-source a script, the script is run in the same environment; or if you run a subshell via ( ) the environment is also preserved (because bash forks, preserving its complete state, rather than reinitialising using the process environment).
The limitation referenced in #lesmana's answer arises because the POSIX environment is simply name=value pairs with no extra meaning, so there's no agreed way to encode or format typed variables, see below for an interesting bash quirk regarding functions , and an upcoming change in bash-4.3(proposed array feature abandoned).
There are a couple of simple ways to do this using declare -p (built-in) to output some of the bash environment as a set of one or more declare statements which can be used reconstruct the type and value of a "name". This is basic serialisation, but with rather less of the complexity some of the other answers imply. declare -p preserves array indexes, sparse arrays and quoting of troublesome values. For simple serialisation of an array you could just dump the values line by line, and use read -a myarray to restore it (works with contiguous 0-indexed arrays, since read -a automatically assigns indexes).
These methods do not require any modification of the script(s) you are passing the arrays to.
declare -p array1 array2 > .bash_arrays # serialise to an intermediate file
bash -c ". .bash_arrays; . otherscript.sh" # source both in the same environment
Variations on the above bash -c "..." form are sometimes (mis-)used in crontabs to set variables.
Alternatives include:
declare -p array1 array2 > .bash_arrays # serialise to an intermediate file
BASH_ENV=.bash_arrays otherscript.sh # non-interactive startup script
Or, as a one-liner:
BASH_ENV=<(declare -p array1 array2) otherscript.sh
The last one uses process substitution to pass the output of the declare command as an rc script. (This method only works in bash-4.0 or later: earlier versions unconditionally fstat() rc files and use the size returned to read() the file in one go; a FIFO returns a size of 0, and so won't work as hoped.)
In a non-interactive shell (i.e. shell script) the file pointed to by the BASH_ENV variable is automatically sourced. You must make sure bash is correctly invoked, possibly using a shebang to invoke "bash" explicitly, and not #!/bin/sh as bash will not honour BASH_ENV when in historical/POSIX mode.
If all your array names happen to have a common prefix you can use declare -p ${!myprefix*} to expand a list of them, instead of enumerating them.
You probably should not attempt to export and re-import the entire bash environment using this method, some special bash variables and arrays are read-only, and there can be other side-effects when modifying special variables.
(You could also do something slightly disagreeable by serialising the array definition to an exportable variable, and using eval, but let's not encourage the use of eval ...
$ array=([1]=a [10]="b c")
$ export scalar_array=$(declare -p array)
$ bash # start a new shell
$ eval $scalar_array
$ declare -p array
declare -a array='([1]="a" [10]="b c")'
)
As referenced above, there's an interesting quirk: special support for exporting functions through the environment:
function myfoo() {
echo foo
}
with export -f or set +a to enable this behaviour, will result in this in the (process) environment, visible with printenv:
myfoo=() { echo foo
}
The variable is functionname (or functioname() for backward compatibility) and its value is () { functionbody }.
When a subsequent bash process starts it will recreate a function from each such environment variable. If you peek into the bash-4.2 source file variables.c you'll see variables starting with () { are handled specially. (Though creating a function using this syntax with declare -f is forbidden.) Update: The "shellshock" security issue is related to this feature, contemporary systems may disable automatic function import from the environment as a mitigation.
If you keep reading though, you'll see an #if 0 (or #if ARRAY_EXPORT) guarding code that checks variables starting with ([ and ending with ), and a comment stating "Array variables may not yet be exported". The good news is that in the current development version bash-4.3rc2 the ability to export indexed arrays (not associative) is enabled. This feature is not likely to be enabled, as noted above.
We can use this to create a function which restores any array data required:
% function sharearray() {
array1=(a b c d)
}
% export -f sharearray
% bash -c 'sharearray; echo ${array1[*]}'
So, similar to the previous approach, invoke the child script with:
bash -c "sharearray; . otherscript.sh"
Or, you can conditionally invoke the sharearray function in the child script by adding at some appropriate point:
declare -F sharearray >/dev/null && sharearray
Note there is no declare -a in the sharearray function, if you do that the array is implicitly local to the function, not what is wanted. bash-4.2 supports declare -g that makes a variable declared in a function into a global, so declare -ga can then be used. (Since associative arrays require a declare -A you won't be able to use this method for global associative arrays prior to bash-4.2, from v4.2 declare -Ag will work as hoped.) The GNU parallel documentation has useful variation on this method, see the discussion of --env in the man page.
Your question as phrased also indicates you may be having problems with export itself. You can export a name after you've created or modified it. "exportable" is a flag or property of a variable, for convenience you can also set and export in a single statement. Up to bash-4.2 export expects only a name, either a simple (scalar) variable or function name are supported.
Even if you could (in future) export arrays, exporting selected indexes (a slice) may not be supported (though since arrays are sparse there's no reason it could not be allowed). Though bash also supports the syntax declare -a name[0], the subscript is ignored, and "name" is simply a normal indexed array.
Jeez. I don't know why the other answers made this so complicated. Bash has nearly built-in support for this.
In the exporting script:
myArray=( ' foo"bar ' $'\n''\nbaz)' ) # an array with two nasty elements
myArray="${myArray[#]#Q}" ./importing_script.sh
(Note, the double quotes are necessary for correct handling of whitespace within array elements.)
Upon entry to importing_script.sh, the value of the myArray environment variable comprises these exact 26 bytes:
' foo"bar ' $'\n\\nbaz)'
Then the following will reconstitute the array:
eval "myArray=( ${myArray} )"
CAUTION! Do not eval like this if you cannot trust the source of the myArray environment variable. This trick exhibits the "Little Bobby Tables" vulnerability. Imagine if someone were to set the value of myArray to ) ; rm -rf / #.
The environment is just a collection of key-value pairs, both of which are character strings. A proper solution that works for any kind of array could either
Save each element in a different variable (e.g. MY_ARRAY_0=myArray[0]). Gets complicated because of the dynamic variable names.
Save the array in the file system (declare -p myArray >file).
Serialize all array elements into a single string.
These are covered in the other posts. If you know that your values never contain a certain character (for example |) and your keys are consecutive integers, you can simply save the array as a delimited list:
export MY_ARRAY=$(IFS='|'; echo "${myArray[*]}")
And restore it in the child process:
IFS='|'; myArray=($MY_ARRAY); unset IFS
Based on #mr.spuratic use of BASH_ENV, here I tunnel $# through script -f -c
script -c <command> <logfile> can be used to run a command inside another pty (and process group) but it cannot pass any structured arguments to <command>.
Instead <command> is a simple string to be an argument to the system library call.
I need to tunnel $# of the outer bash into $# of the bash invoked by script.
As declare -p cannot take #, here I use the magic bash variable _ (with a dummy first array value as that will get overwritten by bash). This saves me trampling on any important variables:
Proof of concept:
BASH_ENV=<( declare -a _=("" "$#") && declare -p _ ) bash -c 'set -- "${_[#]:1}" && echo "$#"'
"But," you say, "you are passing arguments to bash -- and indeed I am, but these are a simple string of known character. Here is use by script
SHELL=/bin/bash BASH_ENV=<( declare -a _=("" "$#") && declare -p _ && echo 'set -- "${_[#]:1}"') script -f -c 'echo "$#"' /tmp/logfile
which gives me this wrapper function in_pty:
in_pty() {
SHELL=/bin/bash BASH_ENV=<( declare -a _=("" "$#") && declare -p _ && echo 'set -- "${_[#]:1}"') script -f -c 'echo "$#"' /tmp/logfile
}
or this function-less wrapper as a composable string for Makefiles:
in_pty=bash -c 'SHELL=/bin/bash BASH_ENV=<( declare -a _=("" "$$#") && declare -p _ && echo '"'"'set -- "$${_[#]:1}"'"'"') script -qfc '"'"'"$$#"'"'"' /tmp/logfile' --
...
$(in_pty) test --verbose $# $^
I was editing a different post and made a mistake. Augh. Anyway, perhaps this might help?
https://stackoverflow.com/a/11944320/1594168
Note that because the shell's array format is undocumented on bash or any other shell's side,
it is very difficult to return a shell array in platform independent way.
You would have to check the version, and also craft a simple script that concatinates all
shell arrays into a file that other processes can resolve into.
However, if you know the name of the array you want to take back home then there is a way, while a bit dirty.
Lets say I have
MyAry[42]="whatever-stuff";
MyAry[55]="foo";
MyAry[99]="bar";
So I want to take it home
name_of_child=MyAry
take_me_home="`declare -p ${name_of_child}`";
export take_me_home="${take_me_home/#declare -a ${name_of_child}=/}"
We can see it being exported, by checking from a sub-process
echo ""|awk '{print "from awk =["ENVIRON["take_me_home"]"]"; }'
Result :
from awk =['([42]="whatever-stuff" [55]="foo" [99]="bar")']
If we absolutely must, use the env var to dump it.
env > some_tmp_file
Then
Before running the another script,
# This is the magic that does it all
source some_tmp_file
As lesmana reported, you cannot export arrays. So you have to serialize them before passing through the environment. This serialization useful other places too where only a string fits (su -c 'string', ssh host 'string'). The shortest code way to do this is to abuse 'getopt'
# preserve_array(arguments). return in _RET a string that can be expanded
# later to recreate positional arguments. They can be restored with:
# eval set -- "$_RET"
preserve_array() {
_RET=$(getopt --shell sh --options "" -- -- "$#") && _RET=${_RET# --}
}
# restore_array(name, payload)
restore_array() {
local name="$1" payload="$2"
eval set -- "$payload"
eval "unset $name && $name=("\$#")"
}
Use it like this:
foo=("1: &&& - *" "2: two" "3: %# abc" )
preserve_array "${foo[#]}"
foo_stuffed=${_RET}
restore_array newfoo "$foo_stuffed"
for elem in "${newfoo[#]}"; do echo "$elem"; done
## output:
# 1: &&& - *
# 2: two
# 3: %# abc
This does not address unset/sparse arrays.
You might be able to reduce the 2 'eval' calls in restore_array.
Although this question/answers are pretty old, this post seems to be the top hit when searching for "bash serialize array"
And, although the original question wasn't quite related to serializing/deserializing arrays, it does seem that the answers have devolved in that direction.
So with that ... I offer my solution:
Pros
All Core Bash Concepts
No Evals
No Sub-Commands
Cons
Functions take variable names as arguments (vs actual values)
Serializing requires having at least one character that is not present in the array
serialize_array.bash
# shellcheck shell=bash
##
# serialize_array
# Serializes a bash array to a string, with a configurable seperator.
#
# $1 = source varname ( contains array to be serialized )
# $2 = target varname ( will contian the serialized string )
# $3 = seperator ( optional, defaults to $'\x01' )
#
# example:
#
# my_arry=( one "two three" four )
# serialize_array my_array my_string '|'
# declare -p my_string
#
# result:
#
# declare -- my_string="one|two three|four"
#
function serialize_array() {
declare -n _array="${1}" _str="${2}" # _array, _str => local reference vars
local IFS="${3:-$'\x01'}"
# shellcheck disable=SC2034 # Reference vars assumed used by caller
_str="${_array[*]}" # * => join on IFS
}
##
# deserialize_array
# Deserializes a string into a bash array, with a configurable seperator.
#
# $1 = source varname ( contains string to be deserialized )
# $2 = target varname ( will contain the deserialized array )
# $3 = seperator ( optional, defaults to $'\x01' )
#
# example:
#
# my_string="one|two three|four"
# deserialize_array my_string my_array '|'
# declare -p my_array
#
# result:
#
# declare -a my_array=([0]="one" [1]="two three" [2]="four")
#
function deserialize_array() {
IFS="${3:-$'\x01'}" read -r -a "${2}" <<<"${!1}" # -a => split on IFS
}
NOTE: This is hosted as a gist here:
https://gist.github.com/TekWizely/c0259f25e18f2368c4a577495cd566cd
[edits]
Logic simplified after running through shellcheck + shfmt.
Added URL for hosted GIST
you (hi!) can use this, dont need writing a file, for ubuntu 12.04, bash 4.2.24
Also, your multiple lines array can be exported.
cat >>exportArray.sh
function FUNCarrayRestore() {
local l_arrayName=$1
local l_exportedArrayName=${l_arrayName}_exportedArray
# if set, recover its value to array
if eval '[[ -n ${'$l_exportedArrayName'+dummy} ]]'; then
eval $l_arrayName'='`eval 'echo $'$l_exportedArrayName` #do not put export here!
fi
}
export -f FUNCarrayRestore
function FUNCarrayFakeExport() {
local l_arrayName=$1
local l_exportedArrayName=${l_arrayName}_exportedArray
# prepare to be shown with export -p
eval 'export '$l_arrayName
# collect exportable array in string mode
local l_export=`export -p \
|grep "^declare -ax $l_arrayName=" \
|sed 's"^declare -ax '$l_arrayName'"export '$l_exportedArrayName'"'`
# creates exportable non array variable (at child shell)
eval "$l_export"
}
export -f FUNCarrayFakeExport
test this example on terminal bash (works with bash 4.2.24):
source exportArray.sh
list=(a b c)
FUNCarrayFakeExport list
bash
echo ${list[#]} #empty :(
FUNCarrayRestore list
echo ${list[#]} #profit! :D
I may improve it here
PS.: if someone clears/improve/makeItRunFaster I would like to know/see, thx! :D
For arrays with values without spaces, I've been using a simple set of functions to iterate through each array element and concatenate the array:
_arrayToStr(){
array=($#)
arrayString=""
for (( i=0; i<${#array[#]}; i++ )); do
if [[ $i == 0 ]]; then
arrayString="\"${array[i]}\""
else
arrayString="${arrayString} \"${array[i]}\""
fi
done
export arrayString="(${arrayString})"
}
_strToArray(){
str=$1
array=${str//\"/}
array=(${array//[()]/""})
export array=${array[#]}
}
The first function with turn the array into a string by adding the opening and closing parentheses and escaping all of the double quotation marks. The second function will strip the quotation marks and the parentheses and place them into a dummy array.
In order export the array, you would pass in all the elements of the original array:
array=(foo bar)
_arrayToStr ${array[#]}
At this point, the array has been exported into the value $arrayString. To import the array in the destination file, rename the array and do the opposite conversion:
_strToArray "$arrayName"
newArray=(${array[#]})
Much thanks to #stéphane-chazelas who pointed out all the problems with my previous attempts, this now seems to work to serialise an array to stdout or into a variable.
This technique does not shell-parse the input (unlike declare -a/declare -p) and so is safe against malicious insertion of metacharacters in the serialised text.
Note: newlines are not escaped, because read deletes the \<newlines> character pair, so -d ... must instead be passed to read, and then unescaped newlines are preserved.
All this is managed in the unserialise function.
Two magic characters are used, the field separator and the record separator (so that multiple arrays can be serialized to the same stream).
These characters can be defined as FS and RS but neither can be defined as newline character because an escaped newline is deleted by read.
The escape character must be \ the backslash, as that is what is used by read to avoid the character being recognized as an IFS character.
serialise will serialise "$#" to stdout, serialise_to will serialise to the varable named in $1
serialise() {
set -- "${#//\\/\\\\}" # \
set -- "${#//${FS:-;}/\\${FS:-;}}" # ; - our field separator
set -- "${#//${RS:-:}/\\${RS:-:}}" # ; - our record separator
local IFS="${FS:-;}"
printf ${SERIALIZE_TARGET:+-v"$SERIALIZE_TARGET"} "%s" "$*${RS:-:}"
}
serialise_to() {
SERIALIZE_TARGET="$1" serialise "${#:2}"
}
unserialise() {
local IFS="${FS:-;}"
if test -n "$2"
then read -d "${RS:-:}" -a "$1" <<<"${*:2}"
else read -d "${RS:-:}" -a "$1"
fi
}
and unserialise with:
unserialise data # read from stdin
or
unserialise data "$serialised_data" # from args
e.g.
$ serialise "Now is the time" "For all good men" "To drink \$drink" "At the \`party\`" $'Party\tParty\tParty'
Now is the time;For all good men;To drink $drink;At the `party`;Party Party Party:
(without a trailing newline)
read it back:
$ serialise_to s "Now is the time" "For all good men" "To drink \$drink" "At the \`party\`" $'Party\tParty\tParty'
$ unserialise array "$s"
$ echo "${array[#]/#/$'\n'}"
Now is the time
For all good men
To drink $drink
At the `party`
Party Party Party
or
unserialise array # read from stdin
Bash's read respects the escape character \ (unless you pass the -r flag) to remove special meaning of characters such as for input field separation or line delimiting.
If you want to serialise an array instead of a mere argument list then just pass your array as the argument list:
serialise_array "${my_array[#]}"
You can use unserialise in a loop like you would read because it is just a wrapped read - but remember that the stream is not newline separated:
while unserialise array
do ...
done
I've wrote my own functions for this and improved the method with the IFS:
Features:
Doesn't call to $(...) and so doesn't spawn another bash shell process
Serializes ? and | characters into ?00 and ?01 sequences and back, so can be used over array with these characters
Handles the line return characters between serialization/deserialization as other characters
Tested in cygwin bash 3.2.48 and Linux bash 4.3.48
function tkl_declare_global()
{
eval "$1=\"\$2\"" # right argument does NOT evaluate
}
function tkl_declare_global_array()
{
local IFS=$' \t\r\n' # just in case, workaround for the bug in the "[#]:i" expression under the bash version lower than 4.1
eval "$1=(\"\${#:2}\")"
}
function tkl_serialize_array()
{
local __array_var="$1"
local __out_var="$2"
[[ -z "$__array_var" ]] && return 1
[[ -z "$__out_var" ]] && return 2
local __array_var_size
eval declare "__array_var_size=\${#$__array_var[#]}"
(( ! __array_var_size )) && { tkl_declare_global $__out_var ''; return 0; }
local __escaped_array_str=''
local __index
local __value
for (( __index=0; __index < __array_var_size; __index++ )); do
eval declare "__value=\"\${$__array_var[__index]}\""
__value="${__value//\?/?00}"
__value="${__value//|/?01}"
__escaped_array_str="$__escaped_array_str${__escaped_array_str:+|}$__value"
done
tkl_declare_global $__out_var "$__escaped_array_str"
return 0
}
function tkl_deserialize_array()
{
local __serialized_array="$1"
local __out_var="$2"
[[ -z "$__out_var" ]] && return 1
(( ! ${#__serialized_array} )) && { tkl_declare_global $__out_var ''; return 0; }
local IFS='|'
local __deserialized_array=($__serialized_array)
tkl_declare_global_array $__out_var
local __index=0
local __value
for __value in "${__deserialized_array[#]}"; do
__value="${__value//\?01/|}"
__value="${__value//\?00/?}"
tkl_declare_global $__out_var[__index] "$__value"
(( __index++ ))
done
return 0
}
Example:
a=($'1 \n 2' "3\"4'" 5 '|' '?')
tkl_serialize_array a b
tkl_deserialize_array "$b" c
I think you can try it this way (by sourcing your script after export):
export myArray=(Hello World)
. yourScript.sh
Suppose there is a C program, which stores its version in a global char* in main.c. Can the buildsystem (gnu make) somehow extract the value of this variable on build time, so that the executable built could have the exact version name as it appears in the program?
What I'd like to achieve is that given the source:
char g_version[] = "Superprogram 1.32 build 1142";
the buildsystem would generate an executable named Superprogram 1.32 build 1142.exe
The shell function allows you to call external applications such as sed that can be used to parse the source for the details required.
Define your version variable from a Macro:
char g_version[] = VERSION;
then make your makefile put a -D argument on the command line when compiling
gcc hack.c -DVERSION=\"Superprogram\ 1.99\"
And of course you should in your example use sed/grep/awk etc to generate your version string.
You can use any combination of unix text tools (grep, sed, awk, perl, tail, ...) in your Makefile in order to extract that information from source file.
Usually the version is defined as a composition of several #define values (like in the arv library for example).
So let's go for a simple and working example:
// myversion.h
#define __MY_MAJOR__ 1
#define __MY_MINOR__ 8
Then in your Makefile:
# Makefile
source_file := myversion.h
MAJOR_Identifier := __MY_MAJOR__
MINOR_Identifier := __MY_MINOR__
MAJOR := `cat $(source_file) | tr -s ' ' | grep "\#define $(MAJOR_Identifier)" | cut -d" " -f 3`
MINOR := `cat $(source_file) | tr -s ' ' | grep '\#define $(MINOR_Identifier)' | cut -d" " -f 3`
all:
#echo "From the Makefile we extract: MAJOR=$(MAJOR) MINOR=$(MINOR)"
Explanation
Here I have used several tools so it is more robust:
tr -s ' ': to remove extra space between elements,
grep: to select the unique line matching our purpose,
cut -d" " -f 3: to extract the third element of the selected line which is the target value!
Note that the define values can be anything (not only numeric).
Beware to use := (not =) see: https://stackoverflow.com/a/10081105/4716013