I have an .xcconfig file that I want to access via the terminal to access variables in the file. Is there a command or is there some way to do this? For example I have a variable called Build_Code = 1234. How would I access that?
Create a script to read the value of a variable.
Ex: .xconfig
var1 = value1
var2 = value2
get_value.bash
#!/bin/bash
#
# get_value.bash <file> <variable>
#
usage()
{
echo "Usage: get_value.bash <file> <variable>"
exit 1
}
#################################################
# Arguments
if [[ $# -eq 2 ]]
then
file="$1"
var="$2"
else
usage
fi
# Check if the file exists
if [[ ! -f "$file" ]]
then
echo "ERROR: file $file does not exist."
exit 2
fi
# Get the variable's value
grep -w "$var" "$file" | cut -d'=' -f2 | tr -d ' '
This simple version assumes the format of the lines is VARIABLE\s*=\s*VALUE.
The tr is to remove spaces around the value.
The VALUE cannot contain spaces.
The <file> argument could be hard coded if you will only ever check .xconfig
Many other solutions could be conceived, depending on the exact requirements, but this does the basic need you put in your question.
Related
I have a variable text file, in which All of my variables are there. I wrote a script through which I get the content of the file, here's the script:
#!/bin/sh
value=`cat dev.txt`
echo "$value"
And I got this output on my terminal screen.
location = "centralus"
location_abr = "cus"
client_name = "fair"
client_name_prefix = "f"
resource_group_postfix = "rg"
project_name = "OTOZ"
environment_name = "devtest"
instance = "04"
Clusterabr= "aks"
But, I want to use the value of the variables which I got in the output. For example, I want to get the value of Clusterabr, But I cannot get it.
Would you please try the following:
#!/bin/bash
declare -A ary # associative array to store name-value pairs
pat='^([^[:space:]]+)[[:space:]]*=[[:space:]]*"([^"]+)"$'
while IFS= read -r line; do
if [[ $line =~ $pat ]]; then
ary[${BASH_REMATCH[1]}]="${BASH_REMATCH[2]}"
fi
done < dev.txt
echo "${ary[Clusterabr]}" # example
Output:
aks
The regex $pat matches the line assiging ${BASH_REMATCH[1]} to the
lvalue and ${BASH_REMATCH[2]} to the rvalue.
ary[$name]="$value" assigns an associative array ary indexed
by "$name" to "$value".
I have an even better solution, based on the source command, as you can see:
Prompt>source dev.txt
Prompt>echo $location
Prompt>centralus
I must admit that you might need to do a small modification in your code, removing the spaces around the = characters, like:
Prompt>cat dev.txt
location="centralus"
location_abr="cus"
...
As you might have guessed, the source command treats your dev.txt file as a piece of script source code.
With the given data/input. With the assumption that there is only one = in each line. With bash and sed.
source <(sed 's/[[:space:]]*=[[:space:]]*/=/' file.txt)
value=`cat dev.txt`
# echo "$value"
#get the value of Clusterabr in dev.txt
value1=`cat dev.txt | grep Clusterabr | cut -d "=" -f2`
echo $value1
#remove "" from the value
value2=`echo $value1 | sed 's/"//g'`
echo $value2
The result:
Below is the do loop script to check whether a variable exists in the .sas7bdat file or not and it's working fine.But is there any way to the check that if all the variable exist in file then assign some value.
rword = var1 var2 var3 var4
for rwords in $rword
do
cat $path | grep -i $rwords
if [ $? -gt 0 ];
then
echo "$rwords DOES NOT EXIST"
exit
else
echo "$rwords EXIST"
fi
done
Thank you
Since all the variable names are unique you can do something like this:
if [ "$(grep --count --extended-regexp --ignore-case 'var1|var2|var3|var4' "$path")" -eq 4 ]
then
[all variables exist]
fi
This, of course, is brittle in several ways:
It would count multiple occurrences of the same variable multiple times, so if you have var3 twice and no var4 it would succeed wrongly.
It would count occurrences of the variable name inside variable values, comments or other data structures in your file.
It would count substring matches such as var2foo.
A better solution would be to use a library which can parse the format reliably (such as sas7bdat). Bash is just bad at parsing any kind of complex file format.
Use grep -q:
check for any of the words
if grep -qE -- "$var1|$var2|$var3|var4" "$path"; then
check for all the words
if grep -q -- "$var1" "$path" && grep -q -- "$var2" "$path" && grep -q -- "$var3" "$path"; then
check for a single word
if ! grep -q -- "$var1" "$path"; then
I am learning bash. I would like to get the return value and matched line by grep at once.
if cat 'file' | grep 'match_word'; then
match_by_grep="$(cat 'file' | grep 'match_word')"
read a b <<< "${match_by_grep}"
fi
In the code above, I used grep twice. I cannot think of how to do it by grep once. I am not sure match_by_grep is always empty even when there is no matched words because cat may output error message.
match_by_grep="$(cat 'file' | grep 'match_word')"
if [[ -n ${match_by_grep} ]]; then
# match_by_grep may be an error message by cat.
# So following a and b may have wrong value.
read a b <<< "${match_by_grep}"
fi
Please tell me how to do it. Thank you very much.
You can avoid the double use of grep by storing the search output in a variable and seeing if it is not empty.
Your version of the script without double grep.
#!/bin/bash
grepOutput="$(grep 'match_word' file)"
if [ ! -z "$grepOutput" ]; then
read a b <<< "${grepOutput}"
fi
An optimization over the above script ( you can remove the temporary variable too)
#!/bin/bash
grepOutput="$(grep 'match_word' file)"
[[ ! -z "$grepOutput" ]] && (read a b <<< "${grepOutput}")
Using double-grep once for checking if-condition and once to parse the search result would be something like:-
#!/bin/bash
if grep -q 'match_word' file; then
grepOutput="$(grep 'match_word' file)"
read a b <<< "${grepOutput}"
fi
When assigning a variable with a string containing a command expansion, the return code is that of the (rightmost) command being expanded.
In other words, you can just use the assignment as the condition:
if grepOutput="$(cat 'file' | grep 'match_word')"
then
echo "There was a match"
read -r a b <<< "${grepOutput}"
(etc)
else
echo "No match"
fi
Is this what you want to achieve?
grep 'match_word' file ; echo $?
$? has a return value of the command run immediately before.
If you would like to keep track of the return value, it will be also useful to have PS1 set up with $?.
Ref: Bash Prompt with Last Exit Code
I'm trying to write a small script that will count entries in a log file, and I'm incrementing a variable (USCOUNTER) which I'm trying to use after the loop is done.
But at that moment USCOUNTER looks to be 0 instead of the actual value. Any idea what I'm doing wrong? Thanks!
FILE=$1
tail -n10 mylog > $FILE
USCOUNTER=0
cat $FILE | while read line; do
country=$(echo "$line" | cut -d' ' -f1)
if [ "US" = "$country" ]; then
USCOUNTER=`expr $USCOUNTER + 1`
echo "US counter $USCOUNTER"
fi
done
echo "final $USCOUNTER"
It outputs:
US counter 1
US counter 2
US counter 3
..
final 0
You are using USCOUNTER in a subshell, that's why the variable is not showing in the main shell.
Instead of cat FILE | while ..., do just a while ... done < $FILE. This way, you avoid the common problem of I set variables in a loop that's in a pipeline. Why do they disappear after the loop terminates? Or, why can't I pipe data to read?:
while read country _; do
if [ "US" = "$country" ]; then
USCOUNTER=$(expr $USCOUNTER + 1)
echo "US counter $USCOUNTER"
fi
done < "$FILE"
Note I also replaced the `` expression with a $().
I also replaced while read line; do country=$(echo "$line" | cut -d' ' -f1) with while read country _. This allows you to say while read var1 var2 ... varN where var1 contains the first word in the line, $var2 and so on, until $varN containing the remaining content.
Always use -r with read.
There is no need to use cut, you can stick with pure bash solutions.
In this case passing read a 2nd var (_) to catch the additional "fields"
Prefer [[ ]] over [ ].
Use arithmetic expressions.
Do not forget to quote variables! Link includes other pitfalls as well
while read -r country _; do
if [[ $country = 'US' ]]; then
((USCOUNTER++))
echo "US counter $USCOUNTER"
fi
done < "$FILE"
minimalist
counter=0
((counter++))
echo $counter
You're getting final 0 because your while loop is being executed in a sub (shell) process and any changes made there are not reflected in the current (parent) shell.
Correct script:
while read -r country _; do
if [ "US" = "$country" ]; then
((USCOUNTER++))
echo "US counter $USCOUNTER"
fi
done < "$FILE"
I had the same $count variable in a while loop getting lost issue.
#fedorqui's answer (and a few others) are accurate answers to the actual question: the sub-shell is indeed the problem.
But it lead me to another issue: I wasn't piping a file content... but the output of a series of pipes & greps...
my erroring sample code:
count=0
cat /etc/hosts | head | while read line; do
((count++))
echo $count $line
done
echo $count
and my fix thanks to the help of this thread and the process substitution:
count=0
while IFS= read -r line; do
((count++))
echo "$count $line"
done < <(cat /etc/hosts | head)
echo "$count"
USCOUNTER=$(grep -c "^US " "$FILE")
Incrementing a variable can be done like that:
_my_counter=$[$_my_counter + 1]
Counting the number of occurrence of a pattern in a column can be done with grep
grep -cE "^([^ ]* ){2}US"
-c count
([^ ]* ) To detect a colonne
{2} the colonne number
US your pattern
Using the following 1 line command for changing many files name in linux using phrase specificity:
find -type f -name '*.jpg' | rename 's/holiday/honeymoon/'
For all files with the extension ".jpg", if they contain the string "holiday", replace it with "honeymoon". For instance, this command would rename the file "ourholiday001.jpg" to "ourhoneymoon001.jpg".
This example also illustrates how to use the find command to send a list of files (-type f) with the extension .jpg (-name '*.jpg') to rename via a pipe (|). rename then reads its file list from standard input.
I'm attempting to read a config file that is formatted as follows:
USER = username
TARGET = arrows
I realize that if I got rid of the spaces, I could simply source the config file, but for security reasons I'm trying to avoid that. I know there is a way to read the config file line by line. I think the process is something like:
Read lines into an array
Filter out all of the lines that start with #
search for the variable names in the array
After that I'm lost. Any and all help would be greatly appreciated. I've tried something like this with no success:
backup2.config>cat ~/1
grep '^[^#].*' | while read one two;do
echo $two
done
I pulled that from a forum post I found, just not sure how to modify it to fit my needs since I'm so new to shell scripting.
http://www.linuxquestions.org/questions/programming-9/bash-shell-program-read-a-configuration-file-276852/
Would it be possible to automatically assign a variable by looping through both arrays?
for (( i = 0 ; i < ${#VALUE[#]} ; i++ ))
do
"${NAME[i]}"=VALUE[i]
done
echo $USER
Such that calling $USER would output "username"? The above code isn't working but I know the solution is something similar to that.
The following script iterates over each line in your input file (vars in my case) and does a pattern match against =. If the equal sign is found it will use Parameter Expansion to parse out the variable name from the value. It then stores each part in it's own array, name and value respectively.
#!/bin/bash
i=0
while read line; do
if [[ "$line" =~ ^[^#]*= ]]; then
name[i]=${line%% =*}
value[i]=${line#*= }
((i++))
fi
done < vars
echo "total array elements: ${#name[#]}"
echo "name[0]: ${name[0]}"
echo "value[0]: ${value[0]}"
echo "name[1]: ${name[1]}"
echo "value[1]: ${value[1]}"
echo "name array: ${name[#]}"
echo "value array: ${value[#]}"
Input
$ cat vars
sdf
USER = username
TARGET = arrows
asdf
as23
Output
$ ./varscript
total array elements: 2
name[0]: USER
value[0]: username
name[1]: TARGET
value[1]: arrows
name array: USER TARGET
value array: username arrows
First, USER is a shell environment variable, so it might be better if you used something else. Using lowercase or mixed case variable names is a way to avoid name collisions.
#!/bin/bash
configfile="/path/to/file"
shopt -s extglob
while IFS='= ' read lhs rhs
do
if [[ $lhs != *( )#* ]]
then
# you can test for variables to accept or other conditions here
declare $lhs=$rhs
fi
done < "$configfile"
This sets the vars in your file to the value associated with it.
echo "Username: $USER, Target: $TARGET"
would output
Username: username, Target: arrows
Another way to do this using keys and values is with an associative array:
Add this line before the while loop:
declare -A settings
Remove the declare line inside the while loop and replace it with:
settings[$lhs]=$rhs
Then:
# set keys
user=USER
target=TARGET
# access values
echo "Username: ${settings[$user]}, Target: ${settings[$target]}"
would output
Username: username, Target: arrows
I have a script which only takes a very limited number of settings, and processes them one at a time, so I've adapted SiegeX's answer to whitelist the settings I care about and act on them as it comes to them.
I've also removed the requirement for spaces around the = in favour of ignoring any that exist using the trim function from another answer.
function trim()
{
local var=$1;
var="${var#"${var%%[![:space:]]*}"}"; # remove leading whitespace characters
var="${var%"${var##*[![:space:]]}"}"; # remove trailing whitespace characters
echo -n "$var";
}
while read line; do
if [[ "$line" =~ ^[^#]*= ]]; then
setting_name=$(trim "${line%%=*}");
setting_value=$(trim "${line#*=}");
case "$setting_name" in
max_foos)
prune_foos $setting_value;
;;
max_bars)
prune_bars $setting_value;
;;
*)
echo "Unrecognised setting: $setting_name";
;;
esac;
fi
done <"$config_file";
Thanks SiegeX. I think the later updates you mentioned does not reflect in this URL.
I had to edit the regex to remove the quotes to get it working. With quotes, array returned is empty.
i=0
while read line; do
if [[ "$line" =~ ^[^#]*= ]]; then
name[i]=${line%% =*}
value[i]=${line##*= }
((i++))
fi
done < vars
A still better version is .
i=0
while read line; do
if [[ "$line" =~ ^[^#]*= ]]; then
name[i]=`echo $line | cut -d'=' -f 1`
value[i]=`echo $line | cut -d'=' -f 2`
((i++))
fi
done < vars
The first version is seen to have issues if there is no space before and after "=" in the config file. Also if the value is missing, i see that the name and value are populated as same. The second version does not have any of these. In addition it trims out unwanted leading and trailing spaces.
This version reads values that can have = within it. Earlier version splits at first occurance of =.
i=0
while read line; do
if [[ "$line" =~ ^[^#]*= ]]; then
name[i]=`echo $line | cut -d'=' -f 1`
value[i]=`echo $line | cut -d'=' -f 2-`
((i++))
fi
done < vars