Uly.me

cloud engineer

Docker Exec

If you want to SSH to a Docker container, use the Docker exec command.

docker exec -it container_name bash

I’m using a Git Bash terminal, so I have to prefix the docker command with winpty.

winpty docker exec -it container_name bash

Result

root@681bbe3f65f1:/var/www/html#

Ctrl-D to exit.

Count String Characters

Here’s a simple little script that displays the number of characters in a string.

#!/bin/bash
if [[ $# -eq 0 ]] ; then echo 'Missing arguments'; exit 0; fi
var=$1
size=${#var}
echo $size

Command:

./length.sh abcdefghijklmnopqrstuvwxyz

Output:

26

Logging Commands

I decided to log my commands for good record keeping. Here’s my script.

#!/bin/bash
if [[ $# -eq 0 ]] ; then echo 'No arguments. Format: ./go.sh script.sh'; exit 0; fi
log=log.txt
echo '-------------------------------' >> $log
date >> $log
echo '---' >> $log
cat $1 >> $log
echo '---' >> $log
/bin/bash $1 2>&1 | tee -a $log

To run.

./go.sh script.sh

Line by line explanation.

  1. Checks for script to run. Exits if there’s no argument.
  2. Sets the log file.
  3. Prints dashes.
  4. Prints the date.
  5. Print 3 dashes.
  6. Prints the commands to the log file.
  7. Print 3 dashes.
  8. Run the command. Send error and standard out to log file.