I would like to print all the value a regex could take in bash. How could I do it, knowing the following code doesn't work.
regex="^db10300[7-9]$"
for valueofregex in $regex
do
echo "$valueofregex";
done
It should of course print :
db103007
db103008
db103009
Thanks in advance
Looks like you are searching for brace expansion:
for value in db10300{7..9}
do
echo "$value"
done
Related
I have an input that could either be dn3321 or
https://domaincom/file?tag=dn3321 and I'm trying to parse the value of tag using shell.
Looks like a regex could do the trick, how would I write a one liner to detect if it's a URL if it is apply the regex to extract the value and if its not just use the value directly.
It's unclear from the question what the full space of possible inputs looks like, but, for the simple cases you gave, you can use parameter expansion:
#!/usr/bin/env bash
in1='dn3321'
in2='https://domaincom/file?tag=dn3321'
echo "${in1#*=}"
echo "${in2#*=}"
# prints "dn3321" twice
This works by removing the first = and any text preceding it.
If you just need to print out a very specific part of the string that is a url you can do it like this:
#!/bin/bash
url="https://domaincom/file?tag=dn3321"
if [[ "$url" =~ "${http,,}" ]] ; then
tag=$(echo $url | cut -d'=' -f2)
fi
if you need something more elaborate I can post an example.
I have the following small code to retrieve file name,
for pfile in ../data/${BENCH}/*.data; do
prot=`expr match ${pfile%.data} "../data/${BENCH}/\(.*\)"`
echo ${prot}
done
pfile%.data is a string like "../data/gpcr/3.4.5.data". However this expression returns 'syntax error'.
I also tried,
prot=`expr match "${pfile%.data}" "../data/${BENCH}/\(.*\)"` AND
prot=`expr match "${pfile%.data}" : "../data/${BENCH}/\(.*\)"` AND
prot=`expr match "${pfile%.data}" '../data/${BENCH}/\(.*\)'`
neither of them worked. I am running these on MacOSX terminal.
Thanks in advance.
According to https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man1/expr.1.html, you need to drop the "match" keyword, which does not exist in this implementation
prot=$(expr ${pfile%.data} : "../data/${BENCH}/\(.*\)")
But since you have bash:
prot=${pfile%.data}
prot=${prot##*/}
echo "$prot"
Or you could do:
prot=$( basename "$pfile" ".data" )
Would just this work for you?
for pfile in ../data/$BENCH/*.data; do
[[ $pfile =~ ^../data/$BENCH/(.*).data$ ]]
prot=${BASH_REMATCH[1]}
echo "$prot"
done
(I guess it's what you're trying to express with the expr match statement).
If I want to look whether a string is alphanumeric and shorter than a certain value, say 10, I would do like this (in BASH+GREP):
if grep '^[0-9a-zA-Z]\{1,10\}$' <<<$1 ; then ...
(BTW: I'm checking for $1, i.e. the first argument)
What if I want the value 10 to be written on a variable, e.g.
UUID_LEN=10
if grep '^[0-9a-zA-Z]\{1,$UUID_LEN\}$' <<<$1 ; then ...
I tried all sort of escapes, braces and so on, but could not avoid the error message
grep: Invalid content of \{\}
After googling and reading bash and grep tutorials I'm pretty convinced it can't be done. Am I wrong? Any way to go around this?
You need to use double quotes so that the shell expands the parameter before passing the resulting argument to grep:
if grep "^[0-9a-zA-Z]\{1,$UUID_LEN\}$" <<<$1 ; then ...
bash can perform regular expression matching itself, without having to start another process to run grep:
if [[ $1 =~ ^[0-9a-zA-Z]{1,$UUID_LEN}$ ]]; then
I believe my question is very simple for someone who knows how to use regular expressions, but I am very new at it and I can't figure out a way to do it. I found many questions similar to this, but none could solve my problem.
In bash, i have a few variables that are of the form
nw=[:digit:]+.a=[:digit:]+
for example, some of these are nw=323.a=42 and nw=90.a=5
I want to retrieve these two numbers and put them in the variables $n and $a.
I tried several tools, including perl, sed, tr and awk, but couldn't get any of these to work, despite I've been googling and trying to fix it for an hour now. tr seems to be the fittest though.
I'd like a piece of code which would achieve the following:
#!/bin/bash
ldir="nw=64.a=2 nw=132.a=3 nw=4949.a=30"
for dir in $ldir; do
retrieve the number following nw and place it in $n
retrieve the number following a and place it in $a
done
... more things...
If you trust your input, you can use eval:
for dir in $ldir ; do
dir=${dir/w=/=} # remove 'w' before '='
eval ${dir/./ } # replace '.' by ' ', evaluate the result
echo $n, $a # show the result so we can check the correctness
done
if you do not trust your input :) use this:
ldir="nw=64.a=2 nw=132.a=3 nw=4949.a=30"
for v in $ldir; do
[[ "$v" =~ ([^\.]*)\.(.*) ]]
declare "n=$(echo ${BASH_REMATCH[1]}|cut -d'=' -f2)"
declare "a=$(echo ${BASH_REMATCH[2]}|cut -d'=' -f2)"
echo "n=$n; a=$a"
done
result in:
n=64; a=2
n=132; a=3
n=4949; a=30
for sure there are more elegant ways, this is just a quick working hack
ldir="nw=64.a=2 nw=132.a=3 nw=4949.a=30"
for dir in $ldir; do
#echo --- line: $dir
for item in $(echo $dir | sed 's/\./ /'); do
val=${item#*=}
name=${item%=*}
#echo ff: $name $val
let "$name=$val"
done
echo retrieve the number following nw and place it in $nw
echo retrieve the number following a and place it in $a
done
How can I find the index of a substring which matches a regular expression on solaris10?
Assuming that what you want is to find the location of the first match of a wildcard in a string using bash, the following bash function returns just that, or empty if the wildcard doesn't match:
function match_index()
{
local pattern=$1
local string=$2
local result=${string/${pattern}*/}
[ ${#result} = ${#string} ] || echo ${#result}
}
For example:
$ echo $(match_index "a[0-9][0-9]" "This is a a123 test")
10
If you want to allow full-blown regular expressions instead of just wildcards, replace the "local result=" line with
local result=$(echo "$string" | sed 's/'"$pattern"'.*$//')
but then you're exposed to the usual shell quoting issues.
The goto options for me are bash, awk and perl. I'm not sure what you're trying to do, but any of the three would likely work well. For example:
f=somestring
string=$(expr match "$f" '.*\(expression\).*')
echo $string
You tagged the question as bash, so I'm going to assume you're asking how to do this in a bash script. Unfortunately, the built-in regular expression matching doesn't save string indices. However, if you're asking this in order to extract the match substring, you're in luck:
if [[ "$var" =~ "$regex" ]]; then
n=${#BASH_REMATCH[*]}
while [[ $i -lt $n ]]
do
echo "capture[$i]: ${BASH_REMATCH[$i]}"
let i++
done
fi
This snippet will output in turn all of the submatches. The first one (index 0) will be the entire match.
You might like your awk options better, though. There's a function match which gives you the index you want. Documentation can be found here. It'll also store the length of the match in RLENGTH, if you need that. To implement this in a bash script, you could do something like:
match_index=$(echo "$var_to_search" | \
awk '{
where = match($0, '"$regex_to_find"')
if (where)
print where
else
print -1
}')
There are a lot of ways to deal with passing the variables in to awk. This combination of piping output and directly embedding one into the awk one-liner is fairly common. You can also give awk variable values with the -v option (see man awk).
Obviously you can modify this to get the length, the match string, whatever it is you need. You can capture multiple things into an array variable if necessary:
match_data=($( ... awk '{ ... print where,RLENGTH,match_string ... }'))
If you use bash 4.x you can source the oobash. A string lib written in bash with oo-style:
http://sourceforge.net/projects/oobash/
String is the constructor function:
String a abcda
a.indexOf a
0
a.lastIndexOf a
4
a.indexOf da
3
There are many "methods" more to work with strings in your scripts:
-base64Decode -base64Encode -capitalize -center
-charAt -concat -contains -count
-endsWith -equals -equalsIgnoreCase -reverse
-hashCode -indexOf -isAlnum -isAlpha
-isAscii -isDigit -isEmpty -isHexDigit
-isLowerCase -isSpace -isPrintable -isUpperCase
-isVisible -lastIndexOf -length -matches
-replaceAll -replaceFirst -startsWith -substring
-swapCase -toLowerCase -toString -toUpperCase
-trim -zfill