Tags: bash
Bourne to Bash
Posted in : Techno Babble
Not all shells are on a beach
I decided to have a play with Bash this weekend as I'd been asked if I could come up with a backup process that was simple enough for the average joe blogs to configure to suit their needs. The script needed to be able to do daily/weekly/monthly backups of selected databases and files/folders and store them on a different server, as a nice touch it also emails the user to let them know that the backup had been done and which databases/files/folders had been included. As well as doing the backups it also keeps the latest 3 in a grandfather/father/son rotation which gives the user 9 potential backups which they can recover from.
As I haven't had a shedload of experience in using bash I spent a fair amount of time hunting round the web looking for clues as to how to do some bits and bats so I thought I'd share some snippets as some of them took a fair amount of searching for/solving and you never know, it may just help someone else in the future ..... probably me 
Code:
#!/usr/bin/env bash | |
# | |
# Read a named file into a variable | |
# | |
| |
# read "file_you_want" into $variable_name | |
contents=$(<foo.txt) | |
| |
echo "${contents}" | |
| |
# | |
# Read a variable file into a variable | |
# | |
| |
# set $variable_name = "file_you_want" | |
my_file='/path/foo.txt' | |
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# read file $variable_name into $variable_name | |
contents=$(<"${my_file}") | |
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echo "${contents}" |
Code:
#!/usr/bin/env bash | |
# | |
# Convert windows line endings to linux line endings | |
# | |
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# set $variable_name = "file_you_want_to_convert" | |
filename='/path/foo.txt' | |
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# remove all \r and save the output to $variable_name.linux | |
tr -d '\r' < ${filename} > ${filename}.linux | |
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# remove original file | |
rm ${filename} -f | |
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# rename $variable_name.linux to $variable_name | |
mv ${filename}.linux ${filename} |
Code:
#!/usr/bin/env bash | |
# | |
# check if a process is already running | |
# | |
| |
# name of the process to check for | |
# add [] around the first letter to stop the "grep process" from showing | |
check_process='[f]oo' | |
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if ps aux | grep -q "${check_process}" | |
then | |
echo 'running' | |
else | |
echo 'not running' | |
fi |
Code:
#!/usr/bin/env bash | |
# | |
# switch between 2 directories | |
# | |
| |
# switch to directory 1 | |
cd /path/foo/ | |
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# show current directory | |
pwd | |
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# switch to directory 2 and "remember" previous directory | |
pushd /path/bar/ | |
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# show current directory | |
pwd | |
| |
# switch back to directory 1 | |
popd | |
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# show current directory | |
pwd | |
| |
# alternative method | |
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# switch to directory 1 | |
cd /path/foo/ | |
| |
# show current directory | |
pwd | |
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# switch to directory 2 and "remember" previous directory | |
pushd /path/bar/ | |
| |
# show current directory | |
pwd | |
| |
# switch back to directory 1 | |
pushd | |
| |
# show current directory | |
pwd | |
| |
# switch back to directory 2 | |
pushd | |
| |
# show current directory | |
pwd |
Code:
#!/usr/bin/env bash | |
# | |
# send an email using echo | |
# | |
| |
echo 'your email content' | mail -s 'your email subject' email_1@domain.com email_2@domain.com | |
| |
# | |
# send an email using a file as content | |
# | |
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mail -s 'your email subject' email_1@domain.com email_2@domain.com < email_content.txt | |
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# | |
# send an email using a variable file for content | |
# | |
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# set $variable_name = "file_you_want_to_use_as_content" | |
email_body='/path/foo.txt' | |
| |
mail -s 'your email subject' email_1@domain.com email_2@domain.com < ${email_body} | |
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# | |
# send an email using a file and replace "%placeholders%" with variables | |
# | |
| |
# set $variable_name = "file_you_want_to_use_as_content" | |
email_body='/path/foo.txt' | |
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# set $variable_name = "replacement_value" | |
foo='bar' | |
| |
# replace the placeholders and email the results | |
# replaces %placeholder% with $foo | |
sed -e "s!%placeholder%!${foo}!;" ${email_body}" | mail -s 'your email subject' email_1@domain.com email_2@domain.com |
Code:
#!/usr/bin/env bash | |
# | |
# find the directory your script lives in | |
# | |
| |
foo= `dirname $0` | |
echo $foo |
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