I often see this command in node.js programs: NODE_ENV=test node app.js which sets the NODE_ENV variable to test and works. I also read here https://en.wikipedia.org/wiki/Environment_variable that this should work for any shell command, but running some tests on my own, here is what I see
$ HELLO="WORLD"
$ HELLO="MARS" echo "$HELLO"
WORLD
$
I would expect this to print MARS. Is there something I am missing here?
The syntax VAR=value command means that the command will be invoked with the environment variable VAR set to VALUE, and this will apply only for the scope of that command.
However, when you are using the command line:
HELLO="MARS" echo "$HELLO"
The shell first interprets the "$HELLO" parameter, determines that it is WORLD, and then what it actually does is run:
HELLO="MARS" echo "WORLD"
So the echo may have the HELLO variable set, but it doesn't affect what it prints - it has already been interpreted before.
Doing
HELLO="MARS"; echo "$HELLO"
does something else entirely. First it sets HELLO to MARS in the current shell, and then it goes on to interpret the echo command. By this time HELLO contains MARS, not WORLD. But this is an entirely different effect - the variable HELLO stays with the value MARS, which is not the case in the command without the ;.
Your problem is that echo is just a poor choice for a demonstartion of this. You can do other demonstrations to prove that HELLO is changed properly:
HELLO="MARS" eval 'echo $HELLO'
In this case, the shell will not interpret the $HELLO because it is within a string in single quotes. It will first put MARS in HELLO, and then call the eval 'echo $HELLO' with that variable set. The eval command with then run echo $HELLO, and you'll get the output you were expecting.
This syntax is best used for things that don't use the given variable as part of the command line, but rather use it internally.
Other answers are correct, but here a refinement :
There are 2 cases in fact when defining a list of variable separated by spaces in bash whether it ends or not with a command.
VAR1=value1 VAR2=value2 ... VARn=valuen command arg1 arg2 ... argn
and
VAR1=value1 VAR2=value2 ... VARn=valuen
don't export VAR1 ... VARn the same way.
In first case VAR1 ... VARn will be set only for command and will then not be exported to current shell.
In second case VAR1 ... VARn will alter current shell.
then ( remark that ';' is very same of using a new line )
HELLO=WORLD
HELLO=MARS echo "i don't export HELLO."
echo "HELLO=$HELLO"
will display
i don't export HELLO.
HELLO=WORLD
and
HELLO=WORLD
HELLO=MARS ; echo "i did export HELLO."
echo "HELLO=$HELLO"
will display
i did export HELLO.
HELLO=MARS
Related
Is it possible to have fishshell split variables that are in cmd line arguments?
Assume I have a variable $args set like so:
$ set args "-a args"
Now, given this python program (test.py):
import sys
print(sys.argv)
If I run the above in fishshell I get this output:
$ python test.py $args
['test.py', '-a args']
Notice that the arguments are passed as one argument. When I do the equivalent in bash I get this output:
$ python test.py $args
['test.py', '-a', 'params']
Is there someway to make fish behave like bash?
You do not want fish to behave like bash (technically any POSIX compatible shell) with respect to variable expansion. The POSIX behavior is the source of endless problems and is why you need to put double-quotes around almost everything. In fact, most experienced people will tell you to add IFS=$'\n' at the top of your scripts to stop that auto-splitting from happening.
One answer is to use fish's "every var is a list" feature: set args "-a" "args" (the quotes are just for clarity and aren't needed in this example). Each element of the list becomes a separate argument to the command. This will do the right thing even if the args value contains whitespace. The other answer is to explicitly split the string on whitespace using command substitution: a_cmd (string split ' ' $args). This will not do the right thing (in fish or bash) if the args value contains whitespace.
I found a little hack with fish commandline tokenization:
function posix_expand_str --description "Expand a string the POSIX way."
set __posix_expand_str__oldline (commandline)
commandline $argv
commandline -o
commandline $__posix_expand_str__oldline
set -e __posix_expand_str__oldline
end
All strings seem like they were concatenated during testing.
When you realize this answered your question, please accept. It only POSIXes when you ask it to, and does not break strings.
Test results:
> posix_expand_str "hello world"
hello
world
> posix_expand_str "hello 'posix haters' world"
hello
posix haters
world
> posix_expand_str "hello" 'high rep "stackoverflow staff"' "world"
hello
high
rep
stackoverflow staff
world
My script try execute mvn clean install in all projects but before it tried switch to dev branch and pull it.
successString="[INFO] BUILD SUCCESS";
file="mvnoutput";
red=$'\e[1;31m';
grn=$'\e[1;32m';
end=$'\e[0m';
function checkResult
if grep -Fxq "$successString" $file
then
echo -en "${grn}[${1}]Build ok${end}";
else
echo "${red}[${1}]Error in mvn clean install${end}";
exit 1;
fi;
end
function pullAndSwitchDevBranch
git checkout dev;
git pull origin dev;
end
cd api-pay-commons/;
pullAndSwitchDevBranch;
touch mvnoutput;
mvn clean install -U > mvnoutput;
checkResult PAY;
Why I received this error?
line 17: end: command not found ./script.sh: line 20: syntax
error near unexpected token git' ./script.sh: line 20: git checkout dev;'
You have used the "fish" tag, so I'm assuming you are running this with the fish shell.
If so: This is not a valid fish script. Fish is explicitly not POSIX-compatible, so you might want to read up on the syntax. (If not, then please correct your tag)
red=$'\e[1;31m';
Fish does not use var=value to set a variable. It uses set var value.
Fish also does not have the $'' style of quoting. Instead, backslash-escapes are interpreted outside of quotes.
So this would be set red \e"[1;31m". Alternatively, fish offers the set_color builtin, which prints the escape sequence for a given color. So this could be set red (set_color red) (or you could call set_color later).
then
Fish does not use if condition; then dosomething; fi. It's if condition; dosomething; end.
echo -en "${grn}[${1}]Build ok${end}";
Fish does not use "${var}". It also does not call the function arguments $1 et al.
This would be something like echo -ens "$grn" "[$argv[1]]" "Build ok" "$end".
exit 1
Fish currently does not allow exiting from functions. You'll have to return 1 and check the result from the outside.
Additionally, you're using semicolons all over the place, which is not typical style in any shell I'm aware of.
In case you are not using fish, but some POSIX-compatible shell (like bash), this is also not valid. The main (and possibly only) issue is that you are using function something; dosomething; end. In bash, that would be
function something () {
#dostuff
}
And in pure POSIX, that would be
something () {
#dostuff
}
I have a perl script that prints a message. This script is being called by GNU make. In my GNU make, I want to display the message printed out by the script AND store it in a variable also.
I'm doing it this way.
result=`$(PERL) parse.pl report.log` #parse the report
echo $(result) #echo the message here
ifneq ($(strip $$(result)),) #check if message is empty
#if not empty, search for filepath string pattern and exit
echo filepath
exit 1
endif
But it is not displaying the string message from parse.pl.
You are capturing into a shell variable, but then trying to echo a makefile variable (and even if you tried to echo the shell variable, that wouldn't work because make runs each line in a separate shell process).
Changing it to echo the shell varible and all to run in one shell should work:
foo:
result=`$(PERL) parse.pl report.log`; \
echo $$result
but whatever you later need to do to use the captured result would also need to be in the same shell execution.
Apparently you can capture into a makefile variable too, which may be more convenient:
foo:
$(eval result := $(shell $(PERL) parse.pl report.log))
echo $(result)
The critical thing to keep in mind with make is first, that the entire makefile is parsed before any rules are run, and second a makefile has two completely distinct syntaxes in it: makefile syntax for most of it, and shell syntax for the recipes. The shell syntax is run by the shell, not by make: make just starts a shell, hands over the recipe, and waits for the shell to exit to see if it worked or not.
As a result of this you CANNOT combine make constructs like ifeq with shell commands and their results: it cannot work because all the make constructs are parsed first, while the makefile is being read in, and the shell commands are not run until much later, when the target is to be built.
In your case you need to write the entire thing in shell syntax, because you want things to depend on the shell invocation.
So, like this:
foo:
result=`$(PERL) parse.pl report.log`; \
echo $$result; \
if [ "$$result" = "" ]; then \
echo filepath; \
exit 1; \
fi
Note how each line ends with a backslash, so it's appended to the previous line instead of being a separate line: make runs each separate line in a different shell.
Alternatively if you have a new-enough GNU make you can use the one shell feature:
.ONESHELL:
foo:
result=`$(PERL) parse.pl report.log`
echo $$result
if [ "$$result" = "" ]; then
echo filepath
exit 1
fi
I have a python script that I would like to run using rundeck that is invoked as follows:
createInstance.py [-n <name>] <env> <version>
Where name is optional and env and version are required.
e.g. if I want to call the script with a name I would call:
createInstance.py -n test staging 1.2.3.4
If I want to default the name, I would call:
createInstance.py staging 1.2.3.4
The problem i have is that I dont know how to specify the script arguments string in rundeck. I have a job, with 3 options, one for env, version and name and if I define the arguments string as:
-n ${option.name} ${option.env} ${option.version}
Whenever the name is unset, rundeck calls:
createInstance.py -n staging 1.2.3.4
Instead I would like it to omit the -n. Is there any way of doing this? Right now my only option is to change the script to be more forgiving in how it handles the -n, and to always ensure its at the end, e.g.:
createInstance.py staging 1.2.3.4 -n
createInstance.py staging 1.2.3.4 -n test
I would like to avoid making this change though, as I want to be able to use the scripts standalone as well.
Rather than use a command step, try an inline script step. Your inline script can count the number of arguments and if they are set. Then with that logic you can choose how to set the creteInstance.py args.
As #Alex-SF suggests, I've also used an inline script for this, along with a Key Value Data log filter. The script is:
#!/bin/bash
# Parse optional parameters
# https://stackoverflow.com/questions/41233996/passing-optional-parameters-to-rundeck-script
# Arguments to this script should be in the format "flag" "value", eg "-p" ${option.name}
# If value is not missing then return will be "flag value", otherwise blank
echo -n "RUNDECK:DATA:"
while (( "$#" )); do
flag="$1"
value="$2"
if [[ -z "$value" ]] || [[ $value =~ ^\- ]]; then
# no value for this parameter (empty or picking up the next flag)
echo -n ""
shift
else
# value provided for this parameter
echo -n "$flag $value "
shift
shift
fi
done
And the key value data filter uses the pattern ^RUNDECK:DATA:(.*)$ and the name data args. Then I use ${data.args*} as the input for the real command.
It's all rather messy, and I can't find any open issue requesting this as a feature (yet).
Use an inline script and use conditional variable expansion feature from bash.
createInstance.py ${RD_OPTION_NAME:+-n $RD_OPTION_NAME} $RD_OPTION_ENV $RD_OPTION_VERSION
This will omit the first option altogether if it is empty ("").
I want to create scipt to faciliate producing local text file extracts from Hive.
This is to basically execute commands like below:
hive -e "SET hive.cli.print.header=true;SELECT * FROM dropme"|perl -pe 's/(?:\t|^)\KNULL(?=\t|$)//g'>extract/outbound/dropme.txt
While the above works like a charm I find it quite problematic to implement through the parametrized following script (much simplified):
#!/bin/sh
TNAME=dropme
SQL="SELECT * FROM $TNAME"
echo $SQL
echo "SQL: $SQL"
EXTRACMD="hive -e \"SET hive.cli.print.header=true;$SQL\"|perl -pe 'BEGIN{if(defined(\$_=<ARGV>)){s/\b\w+\.//g;print}}s/(?:\t|^)\KNULL(?=\t|$)//g'>extract/outbound/$TNAME.txt"
echo "CMD: $EXTRACMD";
${EXTRACMD}
When run I get: Exception in thread "main" java.lang.NumberFormatException: For input string: "e"
I know there may be many flavours you can print the text or execute command. For instance the line echo $SQL prints me list of files in the directory instead:
SELECT file1.txt file2.txt file3.txt file4.txt FROM dropme
while the next one: echo "SQL: $SQL" gives just what I want: SQL: SELECT * FROM dropme
echo "CMD: $EXTRACMD" prints the (almost) the command to be executed. Almost, as I see \t in perl code being expanded:
CMD: hive -e "SET hive.cli.print.header=true;SELECT * FROM dropme"|perl -pe 'BEGIN{if(defined($_=<ARGV>)){s\w+\.//g;print}}s/(?: |^)\KNULL(?= |$)//g'>extract/outbound/dropme.txt
Maybe that's still ok, but what I want is to be able to copy&paste this command into (other) terminal and execute as the command I put at the top. Ideally I would like that command to be exactly the same (so with \t there)
Biggest problem I have comes when I try to execute it (${EXTRACMD} line). I'm getting the error:
Exception in thread "main" java.lang.NumberFormatException: For input string: "e" …and so on, irrelevant as bash treats every 'word' as single command here. I assume as I don't even know what is really tries to run (prior print attempt obviously doesn't help)
I'm aware that I have multiple options, like:
escaping special characters in the command definition string (like I did with doublequotes)
experimenting with echo and $VAR, '$VAR' or "$VAR"
experimenting with "${EXTRACMD}" or evaluating through eval "${EXTRACMD}"
experimenting with shopt -s extglob or set -f
but as number of combinations is quite large and with my little bash experience I feel it's better to ask for good practice here so my question is:
Is there a way to print a (complex/compound shell) command first and subsequently be able to execute it (exactly as per printed output)? In this case it would be printing the exact command from the top, then executing it the same way as by manually copying that output into terminal prompt and pressing Enter.
Do not construct commands as strings. See http://mywiki.wooledge.org/BashFAQ/050 for details.
That page also talks about a built-in way of getting the shell to tell you what it is running (section 6).
If that doesn't do what you want you can also, with bash, try using printf %q\\n "${arr[*]}".