I have an issue in finding a part of string variable in another string variable, I tried many methods but none worked out..
for example:
echo -e " > Required_keyword: $required_keyword"
send_func GUI WhereAmI
echo -e " > FUNCVALUE: $FUNCVALUE"
flag=`echo $FUNCVALUE|awk '{print match($0,"$required_keyword")}'`;
if [ $flag -gt 0 ];then
echo "Success";
else
echo "fail";
fi
But it always gives fail though there are certain words in variable which matches like
0_Menu/BAA_Record ($required_keyword output string)
Trying to connect to 169.254.98.226 ... OK! Executing sendFunc GUI
WhereAmI Sent Function WhereAmI [OK PageName:
"_0_Menu__47__BAA_Record" ($FUNCVALUE output string)
As we can see here the BAA_Record is common in both of the output still, it always give FAIL
The output echo is
> Required_keyword: 0_Menu/BAA_Record
> FUNCVALUE:
Trying to connect to 169.254.98.226 ... OK!
Executing sendFunc GUI WhereAmI
Sent Function WhereAmI [OK]
PageName: "_0_Menu__47__BAA_Record"
Bash can do wildcard and regex matches inside double square brackets.
if [[ foobar == *oba* ]] # wildcard
if [[ foobar =~ fo*b.r ]] # regex
In your example:
if [[ $FUNCVALUE = *$required_keyword* ]]
if [[ $FUNCVALUE =~ .*$required_keyword.* ]]
Not sure if I understand what you want, but if you need to find out if there's part of string "a" present in variable "b" you can use simply just grep.
grep -q "a" <<< "$b"
[[ "$?" -eq 0 ]] && echo "Found" || echo "Not found"
EDIT: To clarify, grep searches for string a in variable b and returns exit status (see man grep, hence the -q switch). After that you can check for exit status and do whatever you want (either with my example or with regular if statement).
Related
Taken this snippet:
$ [[ ""=="foo" ]] && echo yes || echo no
+ [[ -n ==foo ]]
+ echo yes
yes
How does [[ ""=="foo" ]] turn into [[ -n ==foo ]] ?
The RC was of course missing spaces around == - after adding them, it works as expected:
$ [[ "" == "foo" ]] && echo yes || echo no
+ [[ '' == \f\o\o ]]
+ echo no
no
But still i cannot understand why it behaved like this?
It's not changing the empty string into -n.
The string ""=="foo" is equivalent to the string ==foo. The trace output always shows strings in their simplest format, without unnecessary quotes.
A conditional expression that just contains a single string with no operators is true if the string is not empty. That's what the -n operator tests, so the -x expansion shows it that way.
Any operand that isn't preceded or followed by an operator is treated to have an equal operation as -n <operand>. Operators also need to be isolated with spaces to be distinguished. For a list of operators run help test. Also run help [[ to see how the keyword is different from the [ and test builtins.
Here is my code
vmname="$1"
EXCEPTLIST="desktop-01|desktop-02|desktop-03|desktop-04"
if [[ $vmname != #(${EXCEPTLIST}) ]]; then
echo "${vmname}"
else
echo "Its in the exceptlist"
fi
The above code works perfectly but my question is , the EXCEPTLIST can be a long line, say 100 server names. In that case its hard to put all that names in one line. In that situation is there any way to make the variable EXCEPTLIST to be a multiline variable ? something like as follows:
EXCEPTLIST="desktop-01|desktop-02|desktop-03| \n
desktop-04|desktop-05|desktop-06| \n
desktop-07|desktop-08"
I am not sure but was thinking of possibilities.
Apparently I would like to know the terminology of using #(${})- Is this called variable expansion or what ? Does anyone know the documentation/explain to me about how this works in bash. ?
One can declare an array if the data/string is long/large. Use IFS and printf for the format string, something like:
#!/usr/bin/env bash
exceptlist=(
desktop-01
desktop-02
desktop-03
desktop-04
desktop-05
desktop-06
)
pattern=$(IFS='|'; printf '#(%s)' "${exceptlist[*]}")
[[ "$vmname" != $pattern ]] && echo good
In that situation is there any way to make the variable EXCEPTLIST to be a multiline variable ?
With your given input/data an array is also a best option, something like:
exceptlist=(
'desktop-01|desktop-02|desktop-03'
'desktop-04|desktop-05|desktop-06'
'desktop-07|desktop-08'
)
Check what is the value of $pattern variable one way is:
declare -p pattern
Output:
declare -- pattern="#(desktop-01|desktop-02|desktop-03|desktop-04|desktop-05|desktop-06)"
Need to test/check if $vmname is an empty string too, since it will always be true.
On a side note, don't use all upper case variables for purely internal purposes.
The $(...) is called Command Substitution.
See LESS=+'/\ *Command Substitution' man bash
In addition to what was mentioned in the comments about pattern matching
See LESS=+/'(pattern-list)' man bash
See LESS=+/' *\[\[ expression' man bash
s there any way to make the variable EXCEPTLIST to be a multiline variable ?
I see no reason to use matching. Use a bash array and just compare.
exceptlist=(
desktop-01
desktop-02
desktop-03
desktop-04
desktop-05
desktop-06
)
is_in_list() {
local i
for i in "${#:2}"; do
if [[ "$1" = "$i" ]]; then
return 0
fi
done
return 1
}
if is_in_list "$vmname" "${EXCEPTLIST[#]}"; then
echo "is in exception list ${vmname}"
fi
#(${})- Is this called variable expansion or what ? Does anyone know the documentation/explain to me about how this works in bash. ?
${var} is a variable expansion.
#(...) are just characters # ( ).
From man bash in Compund commands:
[[ expression ]]
When the == and != operators are used, the string to the right of the operator is considered a pattern and matched according to the rules
described below under Pattern Matching, as if the extglob shell option were enabled. ...
From Pattern Matching in man bash:
#(pattern-list)
Matches one of the given patterns
[[ command receives the #(a|b|c) string and then matches the arguments.
There is absolutely no need to use Bash specific regex or arrays and loop for a match, if using grep for raw string on word boundary.
The exception list can be multi-line, it will work as well:
#!/usr/bin/sh
exceptlist='
desktop-01|desktop-02|desktop-03|
deskop-04|desktop-05|desktop-06|
desktop-07|deskop-08'
if printf %s "$exceptlist" | grep -qwF "$1"; then
printf '%s is in the exceptlist\n' "$1"
fi
I wouldn't bother with multiple lines of text. This is would be just fine:
EXCEPTLIST='desktop-01|desktop-02|desktop-03|'
EXCEPTLIST+='desktop-04|desktop-05|desktop-06|'
EXCEPTLIST+='desktop-07|desktop-08'
The #(...) construct is called extended globbing pattern and what it does is an extension of what you probably already know -- wildcards:
VAR='foobar'
if [[ "$VAR" == fo?b* ]]; then
echo "Yes!"
else
echo "No!"
fi
A quick walkthrough on extended globbing examples: https://www.linuxjournal.com/content/bash-extended-globbing
#!/bin/bash
set +o posix
shopt -s extglob
vmname=$1
EXCEPTLIST=(
desktop-01 desktop-02 desktop-03
...
)
if IFS='|' eval '[[ ${vmname} == #(${EXCEPTLIST[*]}) ]]'; then
...
Here's one way to load a multiline string into a variable:
fn() {
cat <<EOF
desktop-01|desktop-02|desktop-03|
desktop-04|desktop-05|desktop-06|
desktop-07|desktop-08
EOF
}
exceptlist="$(fn)"
echo $exceptlist
As to solving your specific problem, I can think of a variety of approaches.
Solution 1, since all the desktop has the same desktop-0 prefix and only differ in the last letter, we can make use of {,} or {..} expansion as follows:
vmname="$1"
found=0
for d in desktop-{01..08}
do
if [[ "$vmname" == $d ]]; then
echo "It's in the exceptlist"
found=1
break
fi
done
if (( !found )); then
echo "Not found"
fi
Solution 2, sometimes, it is good to provide a list in a maintainable clear text list. We can use a while loop and iterate through the list
vmname="$1"
found=0
while IFS= read -r d
do
if [[ "$vmname" == $d ]]; then
echo "It's in the exceptlist"
found=1
break
fi
done <<EOF
desktop-01
desktop-02
desktop-03
desktop-04
desktop-05
desktop-06
desktop-07
desktop-08
EOF
if (( !found )); then
echo "Not found"
fi
Solution 3, we can desktop the servers using regular expressions:
vmname="$1"
if [[ "$vmname" =~ ^desktop-0[1-8]$ ]]; then
echo "It's in the exceptlist"
else
echo "Not found"
fi
Solution 4, we populate an array, then iterate through an array:
vmname="$1"
exceptlist=()
exceptlist+=(desktop-01 desktop-02 desktop-03 deskop-04)
exceptlist+=(desktop-05 desktop-06 desktop-07 deskop-08)
found=0
for d in ${exceptlist[#]}
do
if [[ "$vmname" == "$d" ]]; then
echo "It's in the exceptlist"
found=1
break;
fi
done
if (( !found )); then
echo "Not found"
fi
I have been struggling with this for a long time.
Trying to change colour as part of my prompt depending on the exit code of the last command.
I have reduced my prompt to a minimal example:
Red="\[\033[31m\]"
Green="\[\033[32m\]"
Reset="\[\033[0m\]"
statColour(){
if [[ "$1" == "0" ]]; then
echo -e "${Green} $1 "
else
echo -e "${Red} $1 "
fi
}
export PS1="$(statColour \$?)What Colour? $Reset"
And results in red always being used despite the fact the number is clearly 0 in the first instance.
I have tried [ and $1 -eq 0 with no success. Why isn't this working?
Try this:
Red="\033[35m"
Green="\033[32m"
Reset="\033[0m"
statColour(){
if [[ $1 = 0 ]]; then
echo -e "${Green} $1 "
else
echo -e "${Red} $1 "
fi
}
export PS1="\$(statColour \$?)What Colour? $Reset"
# ^
Color definitions changed
Call of statColour is now done every time, and not only once.
if [[ ]] optimized
For an explanation why you always take the false branch:
You are calling statColour with \$? as argument. The backslash ensures, that the $ is taken literally (and not as the start of a parameter expanson), so you have in effect the literal string $?. Since ? is a wildcard character, it is undergoing filename generation, i.e. the parameter is replaced by all files where the name is a $, followed by a single character. If there are no such files in your directory (which is probably the case), the string $? is passed literally to statColour.
Inside statColour, you wrote
[[ "$1" == "0" ]]
which means that you ask, whether the string $? is equal to the string 0. This is never the case, hence the comparision is always false.
For your problem, you could try this approach (not tested, so you may have to debug it a bit):
statColour() {
# Fetch the exit code of the last program
local last_exit_code=$?
if ((last_exit_code == 0)) # Numeric comparision
then
.....
else
...
fi
# Preserve the exit code
return $last_exit_code
}
and set the prompt as
PS1='$(statColour) '"$Reset"
The single quotes ensure that statColour is evaluated dynamically, while $Reset is in double quotes since it is OK to evaluate it statically.
I'm trying to write a small script to compare my external IP (first three bytes) with the one below:
#!/bin/bash
MYFILE=/home/me/.config/i3/pia
while true
do
IP_EX=$(wget http://ipinfo.io/ip -qO - | cut -d"." -f1,2,3)
if [[ "$IP_EX"=="173.199.65" ]]
then
echo file created
touch $MYFILE
else
echo file deleted
rm -f $MYFILE
fi
echo sleeping
sleep 4
done
This always returns file created, and the else statement is never executed. This is the case even if I replace the $IP_EX with whatever. Why is that?
Bash commands are sensitive to spaces. You need to add spaces around ==.
Observe that this gives the wrong answer:
$ IP_EX=abc; [[ "$IP_EX"=="173.199.65" ]] && echo True
True
By contrast, this version, with spaces, works correctly:
$ IP_EX=abc; [[ "$IP_EX" == "173.199.65" ]] && echo True
$
The problem is that bash sees "$IP_EX"=="173.199.65" as a single string. When given such a single argument, [[ returns true if the string is not empty and false if it is empty:
$ [[ "" ]] && echo True
$ [[ "1" ]] && echo True
True
With the spaces added in, bash sees "$IP_EX" == "173.199.65" as three arguments with the middle argument being ==. It therefore tests for equality. This is what you want.
How can I check for a string in a file path in bash? I am trying:
if [[$(echo "${filePathVar}" | sed 's#//#:#g#') == *"File.java"* ]]
to replace all forward slashes with a colon (:) in the path. It's not working. Bash is seeing the file path string as a file path and throws the error "No such file or directory". The intention is for it to see the file path as a string.
Example: filePathVar could be
**/myloc/src/File.java
in which case the check should return true.
Please note that I am writing this script inside a Jenkins job as a build step.
Updates as of 12/15/15
The following returns Not found, which is wrong.
#!/bin/bash
sources="**/src/TESTS/A.java **/src/TESTS/B.java"
if [[ "${sources}" = ~B.java[^/]*$ ]];
then
echo "Found!!"
else
echo "Not Found!!"
fi
The following returns Found which also also wrong (removed the space around the comparator =).
#!/bin/bash
sources="**/src/TESTS/A.java **/src/TESTS/C.java"
if [[ "${sources}"=~B.java[^/]*$ ]];
then
echo "Found!!"
else
echo "Not Found!!"
fi
The comparison operation is clearly not working.
It is easier to use bash's builtin regex matching facility:
$ filePathVar=/myLoc/src/File.java
if [[ "$filePathVar" =~ File.java[^/]*$ ]]; then echo Match; else echo No Match; fi
Match
Inside [[...]], the operator =~ does regex matching. The regular expression File.java[^/]* matches any string that contains File.java optionally followed by anything except /.
It worked in a simpler way as below:
#!/bin/bash
sources="**/src/TESTS/A.java **/src/TESTS/B.java"
if [[ $sources == *"A.java"* ]]
then
echo "Found!!"
else
echo "Not Found!!"
fi