Avoid repeating variable setup in bash

Question

Bash newbie here! How do I avoid repeating the "PASSGEN=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)" each time in this bash script excerpt?

sqlite variables.db "create table passwords (name TEXT PRIMARY KEY, value TEXT);"
PASSGEN=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)
sqlite variables.db "insert into passwords (name,value) values ('BOOKSTACK_MYSQL_ROOT', '$PASSGEN');"
PASSGEN=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)
sqlite variables.db "insert into passwords (name,value) values ('BOOKSTACK_MYSQL', '$PASSGEN');"
PASSGEN=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)
sqlite variables.db "insert into passwords (name,value) values ('BORG_PASSPHRASE', '$PASSGEN');"
PASSGEN=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)
sqlite variables.db "insert into passwords (name,value) values ('CODE_SERVER_PASS', '$PASSGEN');"
PASSGEN=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)
sqlite variables.db "insert into passwords (name,value) values ('CODE_SERVER_SUDO_PASS', '$PASSGEN');"
PASSGEN=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)
sqlite variables.db "insert into passwords (name,value) values ('EXPORTARR_TOKEN', '$PASSGEN');"
PASSGEN=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)
sqlite variables.db "insert into passwords (name,value) values ('FLAME_PASS', '$PASSGEN');"
PASSGEN=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)
sqlite variables.db "insert into passwords (name,value) values ('FLIGHTAIRMAP_INSTALL_PASS', '$PASSGEN');"

score 2 · Answer 1 · answered May 24 '22 at 12:25

2

A simple solution would be to write a function:

function generate_password {
    </dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12
}

Then, your code snippet becomes:

sqlite variables.db "create table passwords (name TEXT PRIMARY KEY, value TEXT);"
sqlite variables.db "insert into passwords (name,value) values ('BOOKSTACK_MYSQL_ROOT', '$(generate_password)');"
sqlite variables.db "insert into passwords (name,value) values ('BOOKSTACK_MYSQL', '$(generate_password)');"
sqlite variables.db "insert into passwords (name,value) values ('BORG_PASSPHRASE', '$(generate_password)');"
# ...

answered May 24 '22 at 12:25

Green绿色

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Perfect! Thanks for the super fast and concise help! – AnimeAi May 24 '22 at 12:31
No problem. If this solution is what you need, select this answer as "accepted answer". – Green绿色 May 24 '22 at 12:33

score 1 · Answer 2 · answered May 24 '22 at 13:42

One way to do it is to use a loop for the table insertions. Try this Shellcheck-clean code:

sqlite variables.db "create table passwords (name TEXT PRIMARY KEY, value TEXT);"

for name in BOOKSTACK_MYSQL_ROOT BOOKSTACK_MYSQL BORG_PASSPHRASE    \
            CODE_SERVER_PASS CODE_SERVER_SUDO_PASS EXPORTARR_TOKEN  \
            FLAME_PASS FLIGHTAIRMAP_INSTALL_PASS
do
    passgen=$(</dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12)
    sqlite variables.db "insert into passwords (name,value) values ('$name', '$passgen');"
done

See Correct Bash and shell script variable capitalization for an explanation of why I replaced PASSGEN with passgen.

Avoid repeating variable setup in bash

2 Answers2