I have a pretty simple script that is something like the following:
#!/bin/bash
VAR1="$1"
MOREF='sudo run command against $VAR1 | grep name | cut -c7-'
echo $MOREF
When I run this script from the command line and pass it the arguments, I am not getting any output. However, when I run the commands contained within the $MOREF variable, I am able to get output.
How can one take the results of a command that needs to be run within a script, save it to a variable, and then output that variable on the screen?
In addition to backticks `command`, command substitution can be done with $(command) or "$(command)", which I find easier to read, and allows for nesting.
OUTPUT=$(ls -1)
echo "${OUTPUT}"
MULTILINE=$(ls \
-1)
echo "${MULTILINE}"
Quoting (") does matter to preserve multi-line variable values; it is optional on the right-hand side of an assignment, as word splitting is not performed, so OUTPUT=$(ls -1) would work fine.
$(sudo run command)
If you're going to use an apostrophe, you need `, not '. This character is called "backticks" (or "grave accent"):
#!/bin/bash
VAR1="$1"
VAR2="$2"
MOREF=`sudo run command against "$VAR1" | grep name | cut -c7-`
echo "$MOREF"
Some Bash tricks I use to set variables from commands
Sorry, there is a loong answer, but as bash is a shell, where the main goal is to run other unix commands and react on result code and/or output, ( commands are often piped filter, etc... ).
Storing command output in variables is something basic and fundamental.
Therefore, depending on
compatibility (posix)
kind of output (filter(s))
number of variable to set (split or interpret)
execution time (monitoring)
error trapping
repeatability of request (see long running background process, further)
interactivity (considering user input while reading from another input file descriptor)
do I miss something?
First simple, old (obsolete), and compatible way
myPi=`echo '4*a(1)' | bc -l`
echo $myPi
3.14159265358979323844
Compatible, second way
As nesting could become heavy, parenthesis was implemented for this
myPi=$(bc -l <<<'4*a(1)')
Using backticks in script is to be avoided today.
Nested sample:
SysStarted=$(date -d "$(ps ho lstart 1)" +%s)
echo $SysStarted
1480656334
bash features
Reading more than one variable (with Bashisms)
df -k /
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/dm-0 999320 529020 401488 57% /
If I just want a used value:
array=($(df -k /))
you could see an array variable:
declare -p array
declare -a array='([0]="Filesystem" [1]="1K-blocks" [2]="Used" [3]="Available" [
4]="Use%" [5]="Mounted" [6]="on" [7]="/dev/dm-0" [8]="999320" [9]="529020" [10]=
"401488" [11]="57%" [12]="/")'
Then:
echo ${array[9]}
529020
But I often use this:
{ read -r _;read -r filesystem size using avail prct mountpoint ; } < <(df -k /)
echo $using
529020
( The first read _ will just drop header line. ) Here, in only one command, you will populate 6 different variables (shown by alphabetical order):
declare -p avail filesystem mountpoint prct size using
declare -- avail="401488"
declare -- filesystem="/dev/dm-0"
declare -- mountpoint="/"
declare -- prct="57%"
declare -- size="999320"
declare -- using="529020"
Or
{ read -a head;varnames=(${head[#]//[K1% -]});varnames=(${head[#]//[K1% -]});
read ${varnames[#],,} ; } < <(LANG=C df -k /)
Then:
declare -p varnames ${varnames[#],,}
declare -a varnames=([0]="Filesystem" [1]="blocks" [2]="Used" [3]="Available" [4]="Use" [5]="Mounted" [6]="on")
declare -- filesystem="/dev/dm-0"
declare -- blocks="999320"
declare -- used="529020"
declare -- available="401488"
declare -- use="57%"
declare -- mounted="/"
declare -- on=""
Or even:
{ read _ ; read filesystem dsk[{6,2,9}] prct mountpoint ; } < <(df -k /)
declare -p mountpoint dsk
declare -- mountpoint="/"
declare -a dsk=([2]="529020" [6]="999320" [9]="401488")
(Note Used and Blocks is switched there: read ... dsk[6] dsk[2] dsk[9] ...)
... will work with associative arrays too: read _ disk[total] disk[used] ...
Other related sample: Parsing xrandr output: and end of Firefox tab by bash in a size of x% of display size? or at AskUbuntu.com Parsing xrandr output
Dedicated fd using unnamed fifo:
There is an elegent way! In this sample, I will read /etc/passwd file:
users=()
while IFS=: read -u $list user pass uid gid name home bin ;do
((uid>=500)) &&
printf -v users[uid] "%11d %7d %-20s %s\n" $uid $gid $user $home
done {list}</etc/passwd
Using this way (... read -u $list; ... {list}<inputfile) leave STDIN free for other purposes, like user interaction.
Then
echo -n "${users[#]}"
1000 1000 user /home/user
...
65534 65534 nobody /nonexistent
and
echo ${!users[#]}
1000 ... 65534
echo -n "${users[1000]}"
1000 1000 user /home/user
This could be used with static files or even /dev/tcp/xx.xx.xx.xx/yyy with x for ip address or hostname and y for port number or with the output of a command:
{
read -u $list -a head # read header in array `head`
varnames=(${head[#]//[K1% -]}) # drop illegal chars for variable names
while read -u $list ${varnames[#],,} ;do
((pct=available*100/(available+used),pct<10)) &&
printf "WARN: FS: %-20s on %-14s %3d <10 (Total: %11u, Use: %7s)\n" \
"${filesystem#*/mapper/}" "$mounted" $pct $blocks "$use"
done
} {list}< <(LANG=C df -k)
And of course with inline documents:
while IFS=\; read -u $list -a myvar ;do
echo ${myvar[2]}
done {list}<<"eof"
foo;bar;baz
alice;bob;charlie
$cherry;$strawberry;$memberberries
eof
Practical sample parsing CSV files:
As this answer is loong enough, for this paragraph,
I just will let you refer to
this answer to How to parse a CSV file in Bash?, I read a file by using an unnamed fifo, using syntax like:
exec {FD}<"$file" # open unnamed fifo for read
IFS=';' read -ru $FD -a headline
while IFS=';' read -ru $FD -a row ;do ...
... But using bash loadable CSV module.
On my website, you may find the same script, reading CSV as inline document.
Sample function for populating some variables:
#!/bin/bash
declare free=0 total=0 used=0 mpnt='??'
getDiskStat() {
{
read _
read _ total used free _ mpnt
} < <(
df -k ${1:-/}
)
}
getDiskStat $1
echo "$mpnt: Tot:$total, used: $used, free: $free."
Nota: declare line is not required, just for readability.
About sudo cmd | grep ... | cut ...
shell=$(cat /etc/passwd | grep $USER | cut -d : -f 7)
echo $shell
/bin/bash
(Please avoid useless cat! So this is just one fork less:
shell=$(grep $USER </etc/passwd | cut -d : -f 7)
All pipes (|) implies forks. Where another process have to be run, accessing disk, libraries calls and so on.
So using sed for sample, will limit subprocess to only one fork:
shell=$(sed </etc/passwd "s/^$USER:.*://p;d")
echo $shell
And with Bashisms:
But for many actions, mostly on small files, Bash could do the job itself:
while IFS=: read -a line ; do
[ "$line" = "$USER" ] && shell=${line[6]}
done </etc/passwd
echo $shell
/bin/bash
or
while IFS=: read loginname encpass uid gid fullname home shell;do
[ "$loginname" = "$USER" ] && break
done </etc/passwd
echo $shell $loginname ...
Going further about variable splitting...
Have a look at my answer to How do I split a string on a delimiter in Bash?
Alternative: reducing forks by using backgrounded long-running tasks
In order to prevent multiple forks like
myPi=$(bc -l <<<'4*a(1)'
myRay=12
myCirc=$(bc -l <<<" 2 * $myPi * $myRay ")
or
myStarted=$(date -d "$(ps ho lstart 1)" +%s)
mySessStart=$(date -d "$(ps ho lstart $$)" +%s)
This work fine, but running many forks is heavy and slow.
And commands like date and bc could make many operations, line by line!!
See:
bc -l <<<$'3*4\n5*6'
12
30
date -f - +%s < <(ps ho lstart 1 $$)
1516030449
1517853288
So we could use a long running background process to make many jobs, without having to initiate a new fork for each request.
You could have a look how reducing forks make Mandelbrot bash, improve from more than eight hours to less than 5 seconds.
Under bash, there is a built-in function: coproc:
coproc bc -l
echo 4*3 >&${COPROC[1]}
read -u $COPROC answer
echo $answer
12
echo >&${COPROC[1]} 'pi=4*a(1)'
ray=42.0
printf >&${COPROC[1]} '2*pi*%s\n' $ray
read -u $COPROC answer
echo $answer
263.89378290154263202896
printf >&${COPROC[1]} 'pi*%s^2\n' $ray
read -u $COPROC answer
echo $answer
5541.76944093239527260816
As bc is ready, running in background and I/O are ready too, there is no delay, nothing to load, open, close, before or after operation. Only the operation himself! This become a lot quicker than having to fork to bc for each operation!
Border effect: While bc stay running, they will hold all registers, so some variables or functions could be defined at initialisation step, as first write to ${COPROC[1]}, just after starting the task (via coproc).
Into a function newConnector
You may found my newConnector function on GitHub.Com or on my own site (Note on GitHub: there are two files on my site. Function and demo are bundled into one unique file which could be sourced for use or just run for demo.)
Sample:
source shell_connector.sh
tty
/dev/pts/20
ps --tty pts/20 fw
PID TTY STAT TIME COMMAND
29019 pts/20 Ss 0:00 bash
30745 pts/20 R+ 0:00 \_ ps --tty pts/20 fw
newConnector /usr/bin/bc "-l" '3*4' 12
ps --tty pts/20 fw
PID TTY STAT TIME COMMAND
29019 pts/20 Ss 0:00 bash
30944 pts/20 S 0:00 \_ /usr/bin/bc -l
30952 pts/20 R+ 0:00 \_ ps --tty pts/20 fw
declare -p PI
bash: declare: PI: not found
myBc '4*a(1)' PI
declare -p PI
declare -- PI="3.14159265358979323844"
The function myBc lets you use the background task with simple syntax.
Then for date:
newConnector /bin/date '-f - +%s' #0 0
myDate '2000-01-01'
946681200
myDate "$(ps ho lstart 1)" boottime
myDate now now
read utm idl </proc/uptime
myBc "$now-$boottime" uptime
printf "%s\n" ${utm%%.*} $uptime
42134906
42134906
ps --tty pts/20 fw
PID TTY STAT TIME COMMAND
29019 pts/20 Ss 0:00 bash
30944 pts/20 S 0:00 \_ /usr/bin/bc -l
32615 pts/20 S 0:00 \_ /bin/date -f - +%s
3162 pts/20 R+ 0:00 \_ ps --tty pts/20 fw
From there, if you want to end one of background processes, you just have to close its fd:
eval "exec $DATEOUT>&-"
eval "exec $DATEIN>&-"
ps --tty pts/20 fw
PID TTY STAT TIME COMMAND
4936 pts/20 Ss 0:00 bash
5256 pts/20 S 0:00 \_ /usr/bin/bc -l
6358 pts/20 R+ 0:00 \_ ps --tty pts/20 fw
which is not needed, because all fd close when the main process finishes.
As they have already indicated to you, you should use `backticks`.
The alternative proposed $(command) works as well, and it also easier to read, but note that it is valid only with Bash or KornShell (and shells derived from those),
so if your scripts have to be really portable on various Unix systems, you should prefer the old backticks notation.
I know three ways to do it:
Functions are suitable for such tasks:**
func (){
ls -l
}
Invoke it by saying func.
Also another suitable solution could be eval:
var="ls -l"
eval $var
The third one is using variables directly:
var=$(ls -l)
OR
var=`ls -l`
You can get the output of the third solution in a good way:
echo "$var"
And also in a nasty way:
echo $var
Just to be different:
MOREF=$(sudo run command against $VAR1 | grep name | cut -c7-)
When setting a variable make sure you have no spaces before and/or after the = sign. I literally spent an hour trying to figure this out, trying all kinds of solutions! This is not cool.
Correct:
WTFF=`echo "stuff"`
echo "Example: $WTFF"
Will Fail with error "stuff: not found" or similar
WTFF= `echo "stuff"`
echo "Example: $WTFF"
If you want to do it with multiline/multiple command/s then you can do this:
output=$( bash <<EOF
# Multiline/multiple command/s
EOF
)
Or:
output=$(
# Multiline/multiple command/s
)
Example:
#!/bin/bash
output="$( bash <<EOF
echo first
echo second
echo third
EOF
)"
echo "$output"
Output:
first
second
third
Using heredoc, you can simplify things pretty easily by breaking down your long single line code into a multiline one. Another example:
output="$( ssh -p $port $user#$domain <<EOF
# Breakdown your long ssh command into multiline here.
EOF
)"
You need to use either
$(command-here)
or
`command-here`
Example
#!/bin/bash
VAR1="$1"
VAR2="$2"
MOREF="$(sudo run command against "$VAR1" | grep name | cut -c7-)"
echo "$MOREF"
If the command that you are trying to execute fails, it would write the output onto the error stream and would then be printed out to the console.
To avoid it, you must redirect the error stream:
result=$(ls -l something_that_does_not_exist 2>&1)
This is another way and is good to use with some text editors that are unable to correctly highlight every intricate code you create:
read -r -d '' str < <(cat somefile.txt)
echo "${#str}"
echo "$str"
You can use backticks (also known as accent graves) or $().
Like:
OUTPUT=$(x+2);
OUTPUT=`x+2`;
Both have the same effect. But OUTPUT=$(x+2) is more readable and the latest one.
Here are two more ways:
Please keep in mind that space is very important in Bash. So, if you want your command to run, use as is without introducing any more spaces.
The following assigns harshil to L and then prints it
L=$"harshil"
echo "$L"
The following assigns the output of the command tr to L2. tr is being operated on another variable, L1.
L2=$(echo "$L1" | tr [:upper:] [:lower:])
Mac/OSX nowadays come with old Bash versions, ie GNU bash, version 3.2.57(1)-release (arm64-apple-darwin21). In this case, one can use:
new_variable="$(some_command)"
A concrete example:
newvar="$(echo $var | tr -d '123')"
Note the (), instead of the usual {} in Bash 4.
Some may find this useful.
Integer values in variable substitution, where the trick is using $(()) double brackets:
N=3
M=3
COUNT=$N-1
ARR[0]=3
ARR[1]=2
ARR[2]=4
ARR[3]=1
while (( COUNT < ${#ARR[#]} ))
do
ARR[$COUNT]=$((ARR[COUNT]*M))
(( COUNT=$COUNT+$N ))
done
I have been looking all over SO for a working solution but no luck :/
I want to perform the mass insertion using the pipelining feature of redis-cli but I am not able to do so.
I have a JAVA code snippet which create a file containing all the commands to run.
String add = "*4\r\n$4\r\nHSET\r\n$22\r\ndiscountProgramOffers\r\n$" +
key.getBytes().length + "\r\n" + key + "\r\n$" +
json.getBytes().length + "\r\n" + json + "\r\n";
System.out.println(add);
In the above code, I followed mass insertion link present at Redis Documentation site.
And this is a demo String which is getting created.
*4\r\n$4\r\nHSET\r\n$22\r\ndiscountProgramOffers\r\n$5\r\nmykey\r\n$7\r\nmyvalue\r\n
When I run the file which is created by the snippet, sometimes I get nothing, and sometimes I get this error:
Error writing to the server: Connection reset by peer
EX:
echo -e "$(cat massInsert.txt)" | redis/src/redis-cli --pipe
Error writing to the server: Connection reset by peer
Am I doing something wrong??
Please help.
FYI: I referred to these questions:
Redis Mass Insertion
redis - mass inserts and counters
Looks like a simple off-by-one error in creating the RESP protocol string:) There are 21, not 22 characters in the discountProgramOffers hash name.
It worked for me (also with printf instead of echo -e), but only in Alpine's shell ash (see the other answer for details):
# inspect data
$ cat redis-cmd-tst.txt
*4\r\n$4\r\nHSET\r\n$21\r\ndiscountProgramOffers\r\n$5\r\nmykey\r\n$7\r\nmyvalue\r\n
# transfer
$ echo -e $(cat redis-cmd-tst.txt) | redis-cli --pipe -a $REDIS_PASSWORD
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
All data transferred. Waiting for the last reply...
Last reply received from server.
errors: 0, replies: 1
# verify
$ redis-cli -a $REDIS_PASSWORD hget discountProgramOffers mykey
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
"myvalue"
If you are doing everything right, but it still does not work, it may be your linux shell's fault and you may need to switch the shell (e.g. to BusyBox ash on Alpine, where Redis is usually conveniently installed, at least in containerized versions).
Correctly formed RESP strings should display in full (i.e. with each keyword and key or value name in separate line) when using either of these commands:
$ printf $(cat redis-cmd-tst.txt)
*1
$4
HSET
$21
discountProgramOffers
$6
mykey1
$8
myvalue1
$ echo -e $(cat /tmp/tst/redis-cmd-tst.txt)
*1
$4
HSET
$21
discountProgramOffers
$6
mykey1
$8
myvalue1
Currently I've verified it works either in BusyBox ash (linked to /bin/sh) on Alpine:
$ echo $0
/bin/ash
$ /bin/ash --help
BusyBox v1.35.0 (2022-08-01 15:14:44 UTC) multi-call binary.
Usage: ash [-il] [-|+Cabefmnuvx] [-|+o OPT]... [-c 'SCRIPT' [ARG0 ARGS] | FILE ARGS | -s ARGS]
Unix shell interpreter
$ cat /etc/os-release
NAME="Alpine Linux"
ID=alpine
VERSION_ID=3.16.2
PRETTY_NAME="Alpine Linux v3.16"
... while it fails to print correctly RESP files in either shell preinstalled on Ubuntu (so both in bash and in dash, to which sh is linked on Ubuntu):
$ printf $(cat dict-to-redis-working.txt)
$ echo -e $(cat dict-to-redis-working.txt)
31T3
$ echo $0
/bin/dash
$ cat /etc/os-release
NAME="Ubuntu"
VERSION="20.04.5 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.5 LTS"
VERSION_ID="20.04"
UBUNTU_CODENAME=focal
Have a shell script which, in turn, run a java program.
The script is invoked as follows :
./script.sh 1 2 3 4 "ab cd"
The 5th shell argument (ab cd) must be passed as a a java system property, what I'm doing is this :
JAVA_OPTS="-Xmx512M -Dlog4j.defaultInitOverride=true"
if [ "$5" ] ; then
JAVA_OPTS="$JAVA_OPTS -Dconfig.path=$5"
fi
Then, run java (JAVA_EXE & CP have proper values) :
$JAVA_EXE $JAVA_OPTS -classpath $CP com.foo.Main
Receiving this error :
Error: Could not find or load main class cd
If passing "abcd" instead of "ab cd" everything is ok.
If passing inline, just surround the value with quotes :
java -Xmx512M -Dconfig.path="ab cd" com.foo.Main
The problem occurs when a variable must be used.
How should I pass the argument containing spaces correctly ?
Instead of building JAVA_OPTS as a string, you can build it as an array:
JAVA_OPTS=(-Xmx512M -Dlog4j.defaultInitOverride=true)
if [ "$5" ] ; then
JAVA_OPTS+=("-Dconfig.path=$5")
fi
"$JAVA_EXE" "${JAVA_OPTS[#]}" -classpath "$CP" com.foo.Main
(Note: the Bourne shell did not have arrays, and POSIX does not require shells to support them, so this approach is not maximally portable. If you use this approach, make sure the first line of your script is something like #!/bin/bash or #!/bin/zsh and not something like #!/bin/sh.)
The only solution I found is to use a special variable for the problematic param
CONFIG_PATH="-Da=a"
if [ "$5" ] ; then
CONFIG_PATH=-Dconfig.path=$5
fi
$JAVA_EXE $JAVA_OPTS "$CONFIG_PATH" -classpath $CP com.foo.Main
It must have some value, otherwise the empty value will be taken as the name of the main class.
$JAVA_EXE $JAVA_OPTS -classpath $CP com.foo.Main MUST be $JAVA_EXE "$JAVA_OPTS" -classpath $CP com.foo.Main - Pay attention to the double quotes around $CP
EDIT: JAVA_OPTS="$JAVA_OPTS -Dconfig.path=$5" should also be JAVA_OPTS="$JAVA_OPTS -Dconfig.path='"'$5'"'"
I have the following shell script. For some reason the java program's standard error and standard output is not printed to the file "log" but instead always appear in the console. Is there a type some where or am I missing something?
JAVACMD="java -XX:+HeapDumpOnOutOfMemoryError -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=19000 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Xss128k -Xmx700m -jar program.jar >log 2>&1 "
echo "Starting server...";
$JAVACMD&
Regrettably, you will have to use eval if you want to keep the redirection operators in the string value.
Like other shell-special characters, redirection operators are only evaluated if they are not quoted. When you expand the JAVACMD parameter it will split on whitespace, but it will not re-evaluate any special characters it includes. Using eval forces this re-evaluation.
The problem with eval is it forces every character be re-evaluated. In your case, none of the other characters will have any untoward affects. If your string value contained some other shell-special character (e.g. ;(){}…) that you did not want the shell to re-evaluate you would have to escape/quote it inside the string value so that eval would not give it a special meaning.
⋮
eval "$JAVACMD &"
To avoid problems with eval, I suggest moving the redirection out of the string value:
JAVACMD="… program.jar"
⋮
$JAVACMD >log 2>&1 &
Done this way the only characters in the string value that you need to watch out for are the whitespace characters (e.g. if you needed some embedded whitespace in one of the options/arguments; if you run into this you might consider using an array variable or "$#" (a singular, array-like variable available in all Bourne-like shells)).
Have you tried:
JAVACMD="java -XX:+HeapDumpOnOutOfMemoryError -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=19000 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Xss128k -Xmx700m -jar program.jar"
echo "Starting server...";
$JAVACMD >log 2>&1 &
The redirections are considered as arguments to the java command as they are contained in the variable.
You can't actually stick redirections in a variable like that and expect bash to accept them. Simple example:
tesla:~ peter$ ECHOCMD='echo > log 2>&1'
tesla:~ peter$ $ECHOCMD
log 2>&1
I.e. your redirection indicators are becoming simple arguments, passed to your java invocation.
One workaround is to say eval $JAVACMD but it won't make your script any cleaner.
In my Java command-line arguments, any characters after space get ignored. For example,
java test.AskGetCampaignByName "Dummy books"
I get the first argument (args[0]) as "Dummy" only. Single quotes also do not help.
Is there a workaround/fix for this? Could it be because of my terminal settings?
My $TERM is xterm, and $LANG is "en_IN".
The arguments are handled by the shell (I assume you are using Bash under Linux?), so any terminal settings should not affect this.
Since you already have quoted the argument, it ought to work. The only possible explanation I can think of is if your java command is a wrapper script and messes up the escaping of the arguments when passing on to the real program. This is easy to do, or perhaps a bit hard to do correctly.
A correct wrapper script should pass all its arguments on as ${1+"$#"}, and any other version is most likely a bug with regards to being able to handle embedded spaces properly. This is not uncommon to do properly, however also any occurrences of $2 or similar are troublesome and must be written as "$2" (or possibly ${2+"$2"}) in order to handle embedded spaces properly, and this is sinned against a lot.
The reason for the not-so-intuitive syntax ${1+"$#"} is that the original $* joined all arguments as "$1 $2 $3 ..." which did not work for embedded spaces. Then "$#" was introduced that (correctly) expanded to "$1" "$2" "$3" ... for all parameters and if no parameters are given it should expand to nothing. Unfortunately some Unix vendor messed up and made "$#" expand to "" even in case of no arguments, and to work around this the clever (but not so readable) hack of writing ${1+"$#"} was invented, making "$#" only expand if parameter $1 is set (i.e. avoiding expansion in case of no arguments).
If my wrapper assumption is wrong you could try to debug with strace:
strace -o outfile -f -ff -F java test.AskGetCampaignByName "Dummy books"
and find out what arguments are passed to execve. Example from running "strace /bin/echo '1 2' 3":
execve("/bin/echo", ["/bin/echo", "1 2", "3"], [/* 93 vars */]) = 0
brk(0) = 0x2400000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f420075b000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f420075a000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/usr/lib64/alliance/lib/tls/x86_64/libc.so.6", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/usr/lib64/alliance/lib/tls/x86_64", 0x7fff08757cd0) = -1 ENOENT (No such file or directory)
open("/usr/lib64/alliance/lib/tls/libc.so.6", O_RDONLY) = -1 ENOENT (No such file or directory)
...
In case your program needs more than positional arguments (= when the command line usage is important), you should consider options and switches. Apache Commons has a great library for this.
You just have to escape the spaces like this:
normal String: "Hello World!"
escaped String: "Hello" "World!"
That worked for me.
My environment:
23:39:19 Zarathustra#thora:/Users/Zarathustra~$bash -version
GNU bash, version 3.2.48(1)-release (x86_64-apple-darwin11)
Copyright (C) 2007 Free Software Foundation, Inc.
It sounds like you are using a operating system distribution where the java command available to the user is a wrapper which finds the right JVM "somewhere" and invokes it accordingly.
If so, it most likely does not escape the arguments properly when invoking the actual java executable.
What distribution do you use?
Just reassemble the arguments in your Java program:
StringBuilder allArgs = new StringBuilder();
for (int i=0; i < args.length; i++)
{
//System.out.println("arg"+i+": "+args[i]);
allArgs.append(args[i]+" ");
}
// Parse out the args the way you wish using allArgs