How can I check if the parameter inserted $1 is a string of 3 chars in uppercase? For example ABG. another example: GTD
Thanks
Using bash-only regular expression syntax:
#!/usr/bin/env bash
if [[ $1 =~ ^[[:upper:]]{3}$ ]]; then
echo "The first argument is three upper-case characters"
else
echo "The first argument is _not_ three upper-case characters
fi
...or, for compatibility with all POSIX shells, one can use a case statement:
#!/bin/sh
case $1 in
[[:upper:]][[:upper:]][[:upper:]])
echo "The first argument is three upper-case characters";;
*)
echo "The first argument is _not_ three upper-case characters";;
esac
I would use:
LC_ALL=C
[[ "$1" == [A-Z][A-Z][A-Z] ]] || exit 1
Or
LC_ALL=C
if [[ "$1" != [A-Z][A-Z][A-Z] ]]; then
echo "$1: invalid input" >&2
exit 1
fi
As per Charles' comment, A-Z is a character range, which is not equivalent to "all upper case latin letters" in all locales, so we can set the locale with LC_ALL=C.
You can use [[:upper:]] instead of [A-Z] if you don't want to set LC_ALL=C.
Alternatively, there's shopt -s globasciiranges, but it only works in bash version 4.3 or later (and is set by default in version 5.0 and later).
Note also, that using glob patterns in a string comparison is bash specific, and won't work in sh.
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 make a simply bash script to change number version based on the source branch of a merge request, i need increment different value if a feature or a hotfix/bigfix/fix branches names:
#!/bin/bash
if [ $# -eq 0 ]
then
echo -e "\nUsage: $0 MERGE_REQUEST_SOURCE\n"
exit 1
fi
if [ ! -f version ]; then
echo "0.0.0" > version
fi
VERSION=$(cat version)
MERGE_REQUEST_SOURCE=$1
declare -a FEATURE_LIST=("feature")
declare -a HOTFIX_LIST=("fix" "hotfix" "bugfix")
IFS="."
read -a num <<< ${VERSION}
MAJOR=${num[0]}
FEATURE=${num[1]}
HOTFIX=${num[2]}
if [[ ${MERGE_REQUEST_SOURCE} =~ .*${FEATURE_LIST[*]}.* ]]; then
FEATURE=$((${FEATURE}+1))
echo "${MAJOR}.${FEATURE}.${HOTFIX}" > version
elif [[ ${MERGE_REQUEST_SOURCE} =~ .*${HOTFIX_LIST[*]}.* ]]; then
HOTFIX=$((${HOTFIX}+1))
echo "${MAJOR}.${FEATURE}.${HOTFIX}" > version
else
echo -e "Nothing change, exit."
exit 0
fi
I've declared two arrays, FEATURE_LIST that contain only feature and work, if i type ./script.sh feature or ./script.sh feature/foobar it increase the value, instead if i type ./script.sh hotfix or other values combinations of array HOTFIX_LIST nothing happened. Where the error?
Using .*${HOTFIX_LIST[*]}.* is quite a tedious way of representing a string for an alternate match for the regex operator in bash. You can use the | character to represent alternations (because Extended Regular Expressions library is supported) in bash regex operator.
First generate the alternation string from the array into a string
hotfixList=$(IFS="|"; printf '^(%s)$' "${HOTFIX_LIST[*]}")
echo "$hotfixList"
^(fix|hotfix|bugfix)$
The string now represents a regex pattern comprising of three words that will match exactly as is because of the anchors ^ and $.
You can now use this variable in your regex match
[[ ${MERGE_REQUEST_SOURCE} =~ $hotfixList ]]
also for the feature check, just put the whole array expansion with [*] on the RHS which would be sufficient. Also you don't need the greedy matches, since you have the longer string on the LHS the comparison would still hold good.
[[ ${MERGE_REQUEST_SOURCE} =~ ${FEATURE_LIST[*]} ]]
As a side note, always use lower case variable names for user variables. The uppercase names are reserved only for the variables maintained by the shell which are persistent and have special meaning.
The version of bash i use is 4.3.11 and I use 'mcedit' as my script writer. I want to check if a variable contains at least one alphabetical character such that 'harry33' and 'a1111' are deemed valid.
I've tried the code below in my script however an error is returned which states that there is an error with '[[:'
SOLVED
#name = "test123"
read -p "Enter you name: " name
until [[ "$name" =~ [A-Za-z] ]]; do
read -p "Please enter a valid name: " name
done
The code you wrote has a couple of issues with spaces (one you already corrected after the [[) and the spaces around an equal should not exist:
name="test123"
if [[ "$name" =~ [A-Za-z] ]]; then
echo "Please enter valid input: "
fi
The line: "Please enter valid input: " will be printed in this case.
As $name contains several values in the range a-z.
Maybe what you want is the opposite, that the line is printed if the variable contains characters outside the range:
name="test"
if [[ "$name" =~ [^A-Za-z] ]]; then
echo "The input contains characters outside the a-z or A-Z range."
fi
But in this case, the characters accepted may include accented (international) characters like é, è, or ë. Which are in-range in several Language Collate sequences.
That also happens with [^[:alpha:]].
Either you embrace full internationalization or limit yourself to old ASCII:
name="test"
LC_COLLATE=C
if [[ "$name" =~ [^A-Za-z] ]]; then
echo "The input contains characters outside the a-z or A-Z range."
fi
If you want to have as valid names with Alpha and digits, there are two options. One which is very strict (old ASCII ranges):
name="harry33"
LC_COLLATE=C
if [[ "$name" =~ ^[0-9A-Za-z]+$ ]]; then
echo "The input only contains digits and alpha."
fi
The other option will also allow é, ß or đ, etc. (which is perfectly fine for an internationalized name), and the range is defined either by the variable LC_COLLATE or LC_ALL as set in the environment.
name="harry33"
if [[ "$name" =~ ^[[:alnum:]]+$ ]]; then
echo "The input only contains digits and alpha."
fi
This option will reject $%&() and similar.
The portable solution free of bashisms such as [[ would be
case $name in
(*[a-zA-Z]*)
echo "Yay! Got an alphabetic character."
;;
(*)
echo "Hmm, no a-z or A-Z found."
;;
esac
First, Bash is picky about spacing, so have a space after your test brackets [[ and ]] Also, if you are looking for user names, I'd think you'd want it to start with a letter, and if it didn't, then echo your prompt.
if [[ ! $var =~ ^[[:alpha:]] ]]; then
echo -n "Please enter valid input: "
read response
fi
I coded the below code and if no -l or -L option is passes to the script I need to assume (detect) whether a filename was passed as a param. The below third condition only matches if filename is one lowercase character. How can I make it flexible to match upper and lower case letters or variable length of the string?
while [ $# -gt 0 ]
do
case $1 in
-l) echo ls;;
-L) echo ls -l;;
[a-z]) echo filename;;
*) echo usage
exit 1;;
esac
shift
done
Also, how can I include a condition in that case statement that would react to empty $1?
If for example the script is called without any options or filenames.
You can match an empty string with a '') or "") case.
A file name can contain any character--even weird ones likes symbols, spaces, newlines, and control characters--so trying to figure out if you have a file name by looking for letters and numbers isn't the right way to do it. Instead you can use the [ -e filename ] test to check if a string is a valid file name.
You should, by the way, put "$1" in double quotes so your script will work if the file name does contain spaces.
case "$1" in
'') echo empty;;
-l) echo ls;;
-L) echo ls -l;;
*) if [ -e "$1" ]; then
echo filename
else
echo usage >&2 # echo to stderr
exit 1
fi;;
esac
Use getopts to parse options, then treat remaining non-option arguments however you like (such as by testing if they're a file).
you find the information in the bash man page if you search for "Pattern Matching" without the quotes.this does the trick: [a-zA-Z0-9]*)
you should probably read on about pattern matching, regular expressions and so on.
furthermore you should honour john kugelmans hint about the double quotes.
in the following code snippet you can see how to check if no parameter got passed.
#!/bin/sh
case "$1" in
[a-zA-Z0-9]*)
echo "filename"
;;
"")
echo "no data"
;;
esac
#OP, generally if you are using bash, to match case insensitivity you can use shopt and set nocasematch
$ shopt -s nocasematch
to check null in your case statement
case "$var" in
"") echo "empty value";;
esac
You are better off falling into the default case *) and there you can at least check if the file exists with [ -e "$1" ] ... if it doesn't then echo usage and exit 1.
how can I know the number of tokens in a bash variable (whitespace-separated tokens) - or at least, wether it is one or there are more.
The $# expansion will tell you the number of elements in a variable / array. If you're working with a bash version greater than 2.05 or so you can:
VAR='some string with words'
VAR=( $VAR )
echo ${#VAR[#]}
This effectively splits the string into an array along whitespace (which is the default delimiter), and then counts the members of the array.
EDIT:
Of course, this recasts the variable as an array. If you don't want that, use a different variable name or recast the variable back into a string:
VAR="${VAR[*]}"
I can't understand why people are using those overcomplicated bashisms all the time. There's almost always a straight-forward, no-bashism solution.
howmany() { echo $#; }
myvar="I am your var"
howmany $myvar
This uses the tokenizer built-in to the shell, so there's no discrepancy.
Here's one related gotcha:
myvar='*'
echo $myvar
echo "$myvar"
set -f
echo $myvar
echo "$myvar"
Note that the solution from #guns using bash array has the same gotcha.
The following is a (supposedly) super-robust version to work around the gotcha:
howmany() ( set -f; set -- $1; echo $# )
If we want to avoid the subshell, things start to get ugly
howmany() {
case $- in *f*) set -- $1;; *) set -f; set -- $1; set +f;; esac
echo $#
}
These two must be used WITH quotes, e.g. howmany "one two three" returns 3
set VAR='hello world'
echo $VAR | wc -w
here is how you can check.
if [ `echo $VAR | wc -w` -gt 1 ]
then
echo "Hello"
fi
Simple method:
$ VAR="a b c d"
$ set $VAR
$ echo $#
4
To count:
sentence="This is a sentence, please count the words in me."
words="${sentence//[^\ ]} "
echo ${#words}
To check:
sentence1="Two words"
sentence2="One"
[[ "$sentence1" =~ [\ ] ]] && echo "sentence1 has more than one word"
[[ "$sentence2" =~ [\ ] ]] && echo "sentence2 has more than one word"
For a robust, portable sh solution, see #JoSo's functions using set -f.
(Simple bash-only solution for answering (only) the "Is there at least 1 whitespace?" question; note: will also match leading and trailing whitespace, unlike the awk solution below:
[[ $v =~ [[:space:]] ]] && echo "\$v has at least 1 whitespace char."
)
Here's a robust awk-based bash solution (less efficient due to invocation of an external utility, but probably won't matter in many real-world scenarios):
# Functions - pass in a quoted variable reference as the only argument.
# Takes advantage of `awk` splitting each input line into individual tokens by
# whitespace; `NF` represents the number of tokens.
# `-v RS=$'\3'` ensures that even multiline input is treated as a single input
# string.
countTokens() { awk -v RS=$'\3' '{print NF}' <<<"$1"; }
hasMultipleTokens() { awk -v RS=$'\3' '{if(NF>1) ec=0; else ec=1; exit ec}' <<<"$1"; }
# Example: Note the use of glob `*` to demonstrate that it is not
# accidentally expanded.
v='I am *'
echo "\$v has $(countTokens "$v") token(s)."
if hasMultipleTokens "$v"; then
echo "\$v has multiple tokens."
else
echo "\$v has just 1 token."
fi
Not sure if this is exactly what you meant but:
$# = Number of arguments passed to the bash script
Otherwise you might be looking for something like man wc