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Top Forums UNIX for Beginners Questions & Answers Using read to assign value to bash variable not working Post 303043533 by Chubler_XL on Thursday 30th of January 2020 09:04:36 PM
Old 01-30-2020
This is because commands within a pipeline are run in subshells so the read statement is setting the variables is a subshell which has not impact on the main shell.

You can achieve what you want using process substitution like this:

Code:
# read var1 var2 < <(openstack hypervisor stats show | awk -F'|' 'NR==14{print $2,$3}')
# echo $var1
vcpus

Edit:
Also in bash 4.* and later you can use a shell option to run the last pipeline command in the current shell.
Note this only work for shells without job control, so in an interactive shell (as opposed to a script) you will also need turn off job control (set +m).

Quote:
lastpipe
If set, and job control is not active, the shell runs the last command of a pipeline
not executed in the background in the current shell environment.
Code:
# echo $BASH_VERSION
5.0.7(1)-release
# shopt -s lastpipe
# set +m

# echo A B C | head -1 | read first second rest
# echo $first
A

# set -m
# shopt -u lastpipe


Last edited by Chubler_XL; 01-30-2020 at 10:25 PM..
These 2 Users Gave Thanks to Chubler_XL For This Post:
 

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MYSQLI_STMT.BIND_RESULT(3)						 1						MYSQLI_STMT.BIND_RESULT(3)

mysqli_stmt::bind_result - Binds variables to a prepared statement for result storage

       Object oriented style

SYNOPSIS
bool mysqli_stmt::bind_result (mixed &$var1, [mixed &$...]) DESCRIPTION
Procedural style bool mysqli_stmt_bind_result (mysqli_stmt $stmt, mixed &$var1, [mixed &$...]) Binds columns in the result set to variables. When mysqli_stmt_fetch(3) is called to fetch data, the MySQL client/server protocol places the data for the bound columns into the speci- fied variables $var1, .... Note Note that all columns must be bound after mysqli_stmt_execute(3) and prior to calling mysqli_stmt_fetch(3). Depending on column types bound variables can silently change to the corresponding PHP type. A column can be bound or rebound at any time, even after a result set has been partially retrieved. The new binding takes effect the next time mysqli_stmt_fetch(3) is called. PARAMETERS
o $ stmt -Procedural style only: A statement identifier returned by mysqli_stmt_init(3). o $var1 - The variable to be bound. RETURN VALUES
Returns TRUE on success or FALSE on failure. EXAMPLES
Example #1 Object oriented style <?php $mysqli = new mysqli("localhost", "my_user", "my_password", "world"); if (mysqli_connect_errno()) { printf("Connect failed: %s ", mysqli_connect_error()); exit(); } /* prepare statement */ if ($stmt = $mysqli->prepare("SELECT Code, Name FROM Country ORDER BY Name LIMIT 5")) { $stmt->execute(); /* bind variables to prepared statement */ $stmt->bind_result($col1, $col2); /* fetch values */ while ($stmt->fetch()) { printf("%s %s ", $col1, $col2); } /* close statement */ $stmt->close(); } /* close connection */ $mysqli->close(); ?> Example #2 Procedural style <?php $link = mysqli_connect("localhost", "my_user", "my_password", "world"); /* check connection */ if (!$link) { printf("Connect failed: %s ", mysqli_connect_error()); exit(); } /* prepare statement */ if ($stmt = mysqli_prepare($link, "SELECT Code, Name FROM Country ORDER BY Name LIMIT 5")) { mysqli_stmt_execute($stmt); /* bind variables to prepared statement */ mysqli_stmt_bind_result($stmt, $col1, $col2); /* fetch values */ while (mysqli_stmt_fetch($stmt)) { printf("%s %s ", $col1, $col2); } /* close statement */ mysqli_stmt_close($stmt); } /* close connection */ mysqli_close($link); ?> The above examples will output: AFG Afghanistan ALB Albania DZA Algeria ASM American Samoa AND Andorra SEE ALSO
mysqli_stmt_get_result(3), mysqli_stmt_bind_param(3), mysqli_stmt_execute(3), mysqli_stmt_fetch(3), mysqli_prepare(3), mysqli_stmt_pre- pare(3), mysqli_stmt_init(3), mysqli_stmt_errno(3), mysqli_stmt_error(3). PHP Documentation Group MYSQLI_STMT.BIND_RESULT(3)
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