I have the below if condition in my shell script which uses regular expressions. Basically I wanted to find out if $main contains string $pattrn.
main="$line1"
pattrn="$line"
if [[ $main = #($pattrn) ]];
then
echo $line>>/lawson/prod/work/errval
fi
Even If I have few matching values but this If condition in not returning anything.
Thanks in Advance
I think I have a solution, though there might be a more elegant solution with sed or awk.
#!/bin/ksh
variable1="ABCDEF"
variable2="CDE"
printf "variable1( %s )\n" $variable1
if( echo $variable1 | grep -q $variable2 ); then
printf "variable2 appears in variable1\n"
fi
variable3="GHI"
if( echo $variable1 | grep -q $variable3 ); then
printf "variable3 appears in variable1\n"
else
printf "variable3 does not appears in variable1\n"
fi
Output
variable1( ABCDEF )
variable2 appears in variable1
variable3 does not appears in variable1
Explanation: You are checking the return value of the command in parenthesis to ensure that the result is equal to 0. With the grep after the pipe, you are checking if grep found the string within the output string from the echo.
Hope that helps.
I wanted to find out if $main contains string $pattrn.
if [[ $main = #($pattrn) ]]
This tests for an exactly equal match. To test if $main contains $pattrn, we have to specify that there may be text before and after $pattrn:
if [[ $main = #(*$pattrn*) ]]
By the way, since we have just one pattern, we can do without #(…) as well:
if [[ $main = *$pattrn* ]]
Related
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 am attempting to check for proper formatting at the start of a string in a bash script.
The expected format is like the below where the string must always begin with "ABCDEFG-" (exact letters and order) and the numbers would vary but be at least 3 digits. Everything after the 3rd digit is a do not care.
Expected start of string: "ABCDEFG-1234"
I am using the below code snippet.
[ $(echo "$str" | grep -E "ABCDEFG-[0-9][0-9][0-9]") ] && echo "yes"
str1 = "ABCDEFG-1234"
str2 = "ABCDEFG-1234 - Some more text"
When I use str1 in place of str everything works ok and yes is printed.
When I use str2 in place of str i get the below error
[: ABCDEFG-1234: unary operator expected
I am pretty new to working with bash scripts so any help would be appreciated.
If this is bash, you have no reason to use grep for this at all; the shell has built-in regular expression support.
re="ABCDEFG-[0-9][0-9][0-9]"
[[ $str =~ $re ]] && echo "yes"
That said, you might want your regex to be anchored if you want a match in the beginning rather than anywhere in the content:
re="^ABCDEFG-[0-9][0-9][0-9]"
[[ $str =~ $re ]] && echo "yes"
That said, this doesn't need to be an ERE at all -- a glob-style pattern match would also be adequate:
if [[ $str = ABCDEFG-[0-9][0-9][0-9]* ]]; then echo "yes"; fi
Try grep -E "ABCDEFG-[0-9][0-9][0-9].*"
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).
I'm trying to match any strings that start with /John/ but does not contain / after /John/
if
[ $string == /John/[!/]+ ]; then ....
fi
This is what I got and it doesn't seem to be working.
So I tried
if
[[ $string =~ ^/John/[!/]+$ ]]; then ....
fi
It still didn't work, and so I changed it to
if
[[ $string =~ /John/[^/] ]]; then ....
fi
It worked but will match with all the strings that has / behind /John/ too.
For bash you want [[ $string =~ /John/[^/]*$ ]] -- the end-of-line anchor ensures there are no slashes after the last acceptable slash.
How about "the string starts with '/John/' and doesn't contain any slashes after '/John/'"?
[[ $string = /John/* && $string != /John/*/* ]]
Or you could compare against a parameter expansion that only expands if the conditions are met. This says "after stripping off everything including and after the last slash, the string is /John":
[[ ${string%/*} = /John ]]
In fact, this last solution is the only entirely POSIXLY_STRICT one I can come up with without multiple test expressions.
[ "${string%/*}" = /John ]
By the way, your problem is probably simply be using double-equals inside a single-bracket test expression. bash actually does accept them inside double-bracket test expressions, but a single equals is a better idea.
You can also use plain old grep:
string='/John Lennon/Yoko Ono'
if echo "$string" | grep -q "/John[^/]" ; then
echo "matched"
else
echo "no match found"
fi
This only fails if /John is at the very end of the string... if that's a possibility then you can tweak to handle that case, for instance:
string='/John Lennon/Yoko Ono'
if echo "$string" | grep -qP "(/John[^/])|(/John$)" ; then
echo "matched"
else
echo "no match found"
fi
Not sure what language you're using, but normal negative character classes are prefixed with a ^
e.g.
[^/]
You can also put in start/end qualifiers (clojure example, so Java's regex engine). Usually ^ at beginning and $ at end.
user => (re-matches #"^/[a-zA-Z]+[^/]$" "/John/")
nil
I am making a bash script where I want to find files that are equal to a variable. The equals will then be used.
I want to use "mogrify" to shrink a couple of image files that have the same name as the ones i gather from a list (similar to "dpkg -l"). It is not "dpkg -l" I am using but it is similar. My problem is that it prints all the files not just the equals. I am pretty sure this could be done with awk instead of a for-loop but I do not know how.
prog="`dpkg -l | awk '{print $1}'`"
for file in $dirone* $dirtwo*
do
if [ "basename ${file}" = "${prog}" ]; then
echo ${file} are equal
else
echo ${file} are not equal
fi
done
Could you please help me get this working?
First, I think there's a small typo. if [ "basename ${file}" =... should have backticks inside the double quotes, just like the prog=... line at the top does.
Second, if $prog is a multi-line string (like dpkg -l) you can't really compare a filename to the entire list. Instead you have to compare one item at a time to the filename.
Here's an example using dpkg and /usr/bin
#!/bin/bash
progs="`dpkg -l | awk '{print $2}'`"
for file in /usr/bin/*
do
base=`basename ${file}`
for prog in ${progs}
do
if [ "${base}" = "${prog}" ]; then
echo "${file}" matches "${prog}"
fi
done
done
The condition "$file = $prog" is a single string. You should try "$file" = "$prog" instead.
The following transcript shows the fix:
pax> ls -1 qq*
qq
qq.c
qq.cpp
pax> export xx=qq.cpp
pax> for file in qq* ; do
if [[ "${file} = ${xx}" ]] ; then
echo .....${file} equal
else
echo .....${file} not equal
fi
done
.....qq equal
.....qq.c equal
.....qq.cpp equal
pax> for file in qq* ; do
if [[ "${file}" = "${xx}" ]] ; then
echo .....${file} equal
else
echo .....${file} not equal
fi
done
.....qq not equal
.....qq.c not equal
.....qq.cpp equal
You can see in the last bit of output that only qq.cpp is shown as equal since it's the only one that matches ${xx}.
The reason you're getting true is because that's what non-empty strings will give you:
pax> if [[ "" ]] ; then
echo .....equal
fi
pax> if [[ "x" ]] ; then
echo .....equal
fi
.....equal
That's because that form is the string length checking variation. From the bash manpage under CONDITIONAL EXPRESSIONS:
string
-n string
True if the length of string is non-zero.
Update:
The new code in your question won't quite work as expected. You need:
if [[ "$(basename ${file})" = "${prog}" ]]; then
to actually execute basename and use its output as the first part of the equality check.
you can use case/esac
case "$file" in
"$prog" ) echo "same";;
esac