BASH | DCMST

Convert and merge xlsx files into a db

Wed, 17 May 2023 00:00:00 +0000

 #!/bin/bash

# Loop through all xlsx files in the current directory
for file in *.xlsx
do
 # Convert xlsx file to csv format using xlsx2csv
 xlsx2csv "$file" "${file%.xlsx}.csv"
done

# Combine all csv files into a single file
cat *.csv > combined.csv

#create database
sqlite3 combined.db <<EOF
CREATE TABLE combined (
 Entry VARCHAR,
 Ref FLOAT,
 ...
);
EOF

# Import the content from the combined.csv file
sqlite3 combined.db <<EOF
.mode csv
.import combined.csv combined
EOF

Kill a process running on port x on Linux

Tue, 16 May 2023 00:00:00 +0000

sudo kill -9 `sudo lsof -t -i:[x]`

where [x] is the port number

Circular cropping from BASH

Fri, 12 May 2023 00:00:00 +0000

The drawing should be ~ half of the original image

convert input.png \
 -gravity Center \
 \( -size 1024x1024 \
 xc:Black \
 -fill White \
 -draw 'circle 500 500 500 1' \
 -alpha Copy \
 \) -compose CopyOpacity -composite \
 -trim output.png

Modified grep command

Wed, 10 May 2023 00:00:00 +0000

When executing the command ps aux | grep -rI process, the displayed results appear as follows:

 8176 process
 8189 grep -rI process

The second entry in the result corresponds to the command we just executed. Although this is typically not problematic, it can lead to issues if you intend to use this command within a bash if statement to check whether process is running. In such cases, the command would return true even if process is not running.

To ensure that the command returns nothing when process is not running, you can modify it as follows:

ps aux | grep -rI [p]rocess

The addition of brackets in the regex causes grep to interpret the query in the same way, but it prevents the literal string [p]rocess from matching process_name. Consequently, the modified command produces the following desired output:

8176 process

This behavior is preferable for certain use cases.