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josanangel
Asked: 2022-04-01 14:24:04 +0800 CST 2022-04-01 14:24:04 +0800 CST

My bash script does not properly check the vars $1 and $2 that I pass to the script

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I am making a bash script to make backup copies of db. Basically I want something like:create_backup.sh {database_name} {table_name}

and run mysqldump database_name.table_name > date.sqlsomething like this.

I want database_nameand to table_namebe optional, that is, if they don't come instead of those vars I will select everything : *.*.

But it doesn't do it right for me, this is my script:

#!/bin/bash

now=$( date '+%F_%H:%M:%S' )

database_name='*'
table_name='*'

if [ -n "$1" ]; then
   $database_name="$1"
fi

if [ -n  "$2" ]; then
   $table_name="$2"
fi

echo "$database_name y $table_name"

echo "mysqldump $database_name.$table_name  > $now.sql"

Clarification: Now I am doing an echo to test that I get what I want.

The script doesn't give me an error, but it doesn't do what it should.

linux

1 Answers

  1. Best Answer

    If you need to make one mysqldumpof all the tables in a DB you don't need to pass *. Even so, I will answer the question of how to treat the arguments.

    #!/bin/bash

now=$( date '+%F_%H:%M:%S' )

database_name='*'
table_name='*'

# Si no se pasan argumentos:
if [ $# -eq 0 ]; then
    echo "No se han pasado argumento, se hará backup por defecto de todas las BBDD y tablas."
fi

# Si se pasa el primer argumento (BD) y el segundo (tabla) se asignan:
if [ -n "$1" ] && [ -n "$2" ]; then
    database_name="$1"
    table_name="$2"
# Sino, si se pasa el primer argumento (DB) pero no se pasa el segundo (la tabla), solo asignamos la BD para dejar la tabla como * 
elif [ -n "$1" ] && ! [ -n "$2" ]; then
    database_name=$1
fi

echo "$database_name y $table_name"

    Examples:

    • Without passing arguments:
    (base) [01-04-21 00:53] {devops@devops} (~/python)$ -> bash test.sh 
No se han pasado argumento, se hará backup por defecto de todas las BBDD y tablas.
* y *
    • Passing only the first argument, that is, the DB:
    (base) [01-04-21 00:53] {devops@devops} (~/python)$ -> bash test.sh database
database y *
    • If you pass both, both DB and table:
    (base) [01-04-21 00:53] {devops@devops} (~/python)$ -> bash test.sh database table
database y table

    Note:

    • Dump of a single table from a DB:
    mysqldump -u <db_username> -h <db_host> -p db_name table_name > table_name.sql
    • Dump a DB:
    mysqldump -u <db_username> -h <db_host> -p db_name > database.sql
    • Dump of all DBs:
    mysqldump -u root -p -h <db_host> --all-databases > alldb.sql
    • 2