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Sending A code-block to a command

An Example...

# dummy variable for illustration
$ thisVar="made this var in bash"

# Command: cat
# code block: 2-lines, 1 using a variable!
cat <<EOF
this is a dummy text block.
$thisVar
EOF

Using a loop to do some math

for num in $(seq 1 6)
do 
cat <<EOF
MATH
---
12 * $num = $((12 * $num))
--- --- ---
EOF
done

The above will return:

MATH
---
12 * 1 = 12
--- --- ---
MATH
---
12 * 2 = 24
--- --- ---
MATH
---
12 * 3 = 36
--- --- ---
MATH
---
12 * 4 = 48
--- --- ---
MATH
---
12 * 5 = 60
--- --- ---
MATH
---
12 * 6 = 72
--- --- ---

Make files based on sequence

for num in $(seq 1 6)
do 
  touch file-$num.txt && \
  cat <<EOF > file-$num.txt
this is file numer $num.
  this line is indented.
EOF
done

CRITICAL NOTES HERE:

  • syntax is critical
    • the EOF at the first character of the line, above on the 7th line, is critical. If EOF is indented, the script does not work.
    • the EOF, here, is an arbitrary string - this tells the tool being used here, heredoc, when to STOP reading the next
Tags:
linux
bash
command
heredoc
text
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