if [[ $line == *"option 1"* ]]
then
CURRENT_OPTION=1
fi
if [[ $line == *"option 2"* ]]
then
CURRENT_OPTION=2
fi
if [[ $line =~ "What i want" ]]
then
if [[ $CURRENT_OPTION -eq 1 ]]
then
MEM1=$(awk '/Used heap/ { gsub(/M/, " "); print $4 }')
elif [[ $CURRENT_OPTION -eq 2 ]]
then
MEM2=$(awk '/Used heap/ { gsub(/M/, " "); print $4 }')
fi
fi
Because CURRENT_OPTION is defined within an if, its value is not correct when checked in the third if. How do I pass it out so that it is?
Just declare CURRENT_OPTION at the top, something like:
declare -i CURRENT_OPTION=0
i to declare it as an int.
In all of your if statements you should enclose the variables in double quotes. If the variable is an empty string (or if the variable doesn't exist) then the if statement will not contain enough arguments and will throw an error.
Here is an example:
if [[ $var -eq 1 ]]
then
echo yes
else
echo no
fi
If var is uninitialised, bash will expand the statement to look like this:
if [[ -eq 1 ]]
then
echo yes
else
echo no
fi
There are not enough arguments to make the if statement valid here, and bash will throw an error:
bash: conditional binary operator expected
bash: syntax error near `1'
By wrapping the variable in quotes, this situation is avoided. This statement:
if [[ "$var" -eq 1 ]]
...
is expanded to:
if [[ "" -eq 1 ]]
...
and now the if statement has enough arguments (the first one being an empty string) to parse.
Related
I am writing a bash script that sometimes will use environment variables GIT_DIR and GIT_WORK_TREE. The bash script can only operate correctly if either both variables exist or neither exist. In case there's a technical difference, it makes no difference
This works, but there has to be a better way:
if [[ -z "${GIT_DIR}" ]]; then
_GIT_DIR_EXISTS=0
else
_GIT_DIR_EXISTS=1
fi
if [[ -z "${GIT_WORK_TREE}" ]]; then
_GIT_WORK_TREE_EXISTS=0
else
_GIT_WORK_TREE_EXISTS=1
fi
if [[ "${_GIT_DIR_EXISTS}" -ne "${_GIT_WORK_TREE_EXISTS}" ]]; then
echo "GIT_DIR is ${GIT_DIR}"
echo "GIT_WORK_TREE is ${GIT_WORK_TREE}"
echo "Both or none must exist"
exit 1
fi
I tried:
if [[ (-z "${GIT_DIR}") -ne (-z "${GIT_WORK_TREE}") ]]; then
But that gives this error:
bash: syntax error in conditional expression
bash: syntax error near '-ne'
I then resorted to trying semi-random things, with varying errors:
if [[ -z "${GIT_DIR}" -ne -z "${GIT_WORK_TREE}" ]]; then
if [[ [-z "${GIT_DIR}"] -ne [-z "${GIT_WORK_TREE}"] ]]; then
if [[ [[-z "${GIT_DIR}"]] -ne [[-z "${GIT_WORK_TREE}"]] ]]; then
if [[ -z "${GIT_DIR}" ]] ^ [[ -z "${GIT_WORK_TREE}" ]]; then
if { [[ -z "${GIT_DIR}" ]] } -ne { [[ -z "${GIT_WORK_TREE}" ]] }; then
if [[ (( -z "${GIT_DIR}" )) -ne (( -z "${GIT_WORK_TREE}" )) ]]; then
I tried:
if [[ $(test -z "${GIT_DIR}") -ne $(test -z "${GIT_WORK_TREE}") ]]; then
But realized that doesn't work because it's a sub-process, and they'd need to be exported. as Socowl comments, this compares the outputs of the test commands which output nothing, not their exit statuses.
I apologize if this is a duplicate. I've searched here and google for a while, and must not be using the right terminology.
How about this:
if [[ "${GIT_DIR:+set}" != "${GIT_WORK_TREE:+set}" ]]; then
echo "GIT_DIR is '${GIT_DIR}'"
echo "GIT_WORK_TREE is '${GIT_WORK_TREE}'"
echo "Both or none must exist"
exit 1
fi
Explanation: ${var:+value} is a variant of parameter expansion that gives "value" if var is set to a nonempty string, or the empty string if var is unset or empty. So if both vars are unset/empty, it becomes if [[ "" != "" ]]; then, and if they're both set it becomes if [[ "set" != "set" ]]; then etc.
BTW, if you want to test whether the variables are set at all (even if to the empty string), use ${var+value} (note the lack of colon). The bash manual lists the :+ version, but not the + version.
When I execute below script it works fine:
if [[ "[1,2,3]" =~ .*1.* ]]; then
techStatus=1
else
techStatus=0;
fi
echo $techStatus
Output is 1
But when we changes it to variable it does not work.
var1=[1,2,3]
var2=1
if [[ "$var1" =~ .*"$var2".* ]]; then
techStatus=1
else
techStatus=0;
fi
echo $techStatus
Output is 0.
Please help me figure out what is wrong here.
A better & readable approach would be to convert var1 to array and loop through var1.
var1=(1 2 3)
var2=1
for elem in "${var1[#]}"; do
if [[ "$elem" -eq "$var2" ]]; then
techStatus=1
break
else
techStatus=0
fi
done
echo "$techStatus"
I am very new to Bash Scripting and I have a question regarding my CheckOurCodingRules.sh script:
I want to search for every 'hPar,' in a textfile and if found it should be checked if there is a also a 'const' in the same row.
Thats what I got so far but there is something wrong here:
while read line
do
if [[ $line == *hPar\,* ]] && [[ $line == *const\*]];then
DOCUMENTATION_TEST_A=1
else
echo DOCUMENTATION_TEST_A=0
fi
done < $INPUT_FILE
if [[DOCUMENTATION_TEST_A=0]];then
echo "error: Rule1: No const before hpar"
fi
There are a couple of issues with your script, see the code below which works for me:
DOCUMENTATION_TEST_A=0 # initial value
while read line
do
# spaces between conditional and brackets, no backslashes
if [[ $line == *hPar,* ]] && [[ $line == *const* ]]
then
DOCUMENTATION_TEST_A=1
break # optional, no need to scan the rest of the file
fi
done < $INPUT_FILE
# spaces and $, -eq is used for numerical comparisons
if [[ $DOCUMENTATION_TEST_A -eq 0 ]];
then
echo "error: Rule1: No const before hpar"
fi
A cleaner solution would be to use grep:
if ! grep "hPar," $INPUT_FILE | grep "const" >/dev/null
then
echo "error: Rule1: No const before hpar"
fi
I try to test if a string starts with a certain prefix. But my script seems not work (I would expect the "if" branch will not get run). Can some Bash expert help to take a look? thanks!
Here is my code and test result:
$ cat testb.bash
#!/bin/bash
my_var="abcdefg";
if [[ "${my_var:0:5}"=="order" ]]; then
echo "value of my_var is ${my_var}.";
fi;
if [[ "${my_var:0:5}" -eq "order" ]]; then
echo "value of my_var is ${my_var}.";
fi;
if [ "${my_var:0:5}"="order" ]; then
echo "value of my_var is ${my_var}.";
fi;
$ bash -x testb.bash
+ my_var=abcdefg
+ [[ -n abcde==order ]]
+ echo 'value of my_var is abcdefg.'
value of my_var is abcdefg.
+ [[ abcde -eq order ]]
+ echo 'value of my_var is abcdefg.'
value of my_var is abcdefg.
+ '[' abcde=order ']'
+ echo 'value of my_var is abcdefg.'
value of my_var is abcdefg.
$
Whitespace is significant in this case. As you can see in the -x output, it understands the first condition as
[[ -n "${my_var:0:5}==order" ]]
Moreover, to test for a prefix, you can use a pattern:
[[ $my_var == order* ]]
To test the existence of substring, you can use either of these:
if [[ "$j" =~ string1 ]]; then
if [[ $j == *string1* ]]; then
In your particular case, you miss a space surounding ==, so instead of
if [[ "${my_var:0:5}"=="order" ]]; then
it should be
if [[ "${my_var:0:5}" == "order" ]]; then
^ ^
Finally, note that your condition was evaluated as true because it was evaluating if [ "string" ], which is true if string is not empty:
$ [ "a" ] && echo "yes"
yes
Test
$ cat a
#!/bin/bash
my_var="abcdefg";
if [[ "${my_var:0:5}" == "order" ]]; then
echo "value of my_var is ${my_var}."
elif [[ "${my_var:0:5}" == "abcde" ]]; then
echo "yeahaa"
else
echo "is not"
fi
$ ./a
yeahaa
Ok, i tested your code, you shoud such as the following code:
prefix="pre_order";
pre="pre_"
len=${#pre}
echo $len
if [[ "${prefix:0:len}" == "blahvlah" ]] ; then
echo "dddd"
fi;
Notes:
use == for string comparation
for ${} you should initilize a string variable before ${}
use len=${#pre} for lenght of string.
A POSIX-compliant way to test for a prefix is to attempt to remove the prefix, and compare the result to the original string. If the two are the same, the prefix is not present, the removal fails, and the expression expands to the original string.
prefix=foo
string=foobar
if [ "${string#$prefix}" = "$string" ]; then
printf "$string does not start with $prefix\n"
else
printf "$string starts with $prefix\n"
fi
Is it possible to override Bash's test builtin? So that
[[ $1 = 'a' ]]
not just does the test but also outputs which result was expected when it fails? Something like
echo "Expected $1 to be a.'
EDIT
I know this is bad :-).
The test expression compound command does real short-circuiting that affects all expansions.
$ set -x
$ [[ 0 -gt x=1+1 || ++x -eq $(tee /dev/fd/3 <<<$x) && $(echo 'nope' >&3) ]] 3>&1
+ [[ 0 -gt x=1+1 ]]
++ tee /dev/fd/2
2
+ [[ ++x -eq 2 ]]
So yes you could do anything in a single test expression. In reality it's quite rare to have a test produce a side-effect, and almost never used to produce output.
Also yes, reserved words can be overridden. Bash is more lenient with ksh-style function definitions than POSIX style (which still allows some invalid names).
function [[ { [ "${#:1:${##}-1}" ]; }; \[[ -a -o -a -o -a ]] || echo lulz
Yet another forky bomb.
if function function if function if if \function & then \if & fi && \if & then \function & fi && then \function fi
Something like this?
if [[ $1 == 'a' ]]; then
echo "all right";
else
echo 'Expected $1 to be "a"'
fi
Anyway, what's the point of the test if you only expect one answer? Or do you mean that for debugging purposes?
[[ 'a' = 'a' ]] || echo "failed"
[[ 'b' = 'a' ]] || echo "failed"
failed