cut and paste in Bash Scripting - Step-by-Step Execution

Concept Flow - cut and paste

Start

↓

Use 'cut' to extract columns

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Use 'paste' to join columns

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Output combined result

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End

The flow shows extracting parts of text with 'cut', then joining them side-by-side with 'paste' to create combined output.

Execution Sample

Bash Scripting

echo -e "a,b,c\nd,e,f" > file1.txt
cut -d',' -f1 file1.txt > col1.txt
cut -d',' -f3 file1.txt > col3.txt
paste col1.txt col3.txt

Extract first and third columns from a CSV file and paste them side by side.

Execution Table

Step	Command	Action	Output
1	echo -e "a,b,c\nd,e,f" > file1.txt	Create file1.txt with two lines
2	cut -d',' -f1 file1.txt > col1.txt	Extract first column (before first comma)	col1.txt contains: a d
3	cut -d',' -f3 file1.txt > col3.txt	Extract third column (after second comma)	col3.txt contains: c f
4	paste col1.txt col3.txt	Combine col1.txt and col3.txt side by side	a c d f
5	End	No more commands	Execution complete

💡 All commands executed; paste output shows combined columns.

Variable Tracker

Variable/File	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
file1.txt	does not exist	a,b,c d,e,f	a,b,c d,e,f	a,b,c d,e,f	a,b,c d,e,f	a,b,c d,e,f
col1.txt	does not exist	does not exist	a d	a d	a d	a d
col3.txt	does not exist	does not exist	does not exist	c f	c f	c f
paste output	none	none	none	none	a c d f	a c d f

Key Moments - 3 Insights

Why do we use '-d',' and '-f' options with cut?

The '-d',' tells cut to use comma as the separator, and '-f' selects which column to extract. This is shown in steps 2 and 3 where cut extracts columns based on commas.

What does paste do with the two files?

Paste combines lines from two files side by side separated by a tab, as seen in step 4 where col1.txt and col3.txt lines are joined.

Why do we redirect cut output to files before pasting?

Paste works on files or streams line by line, so we save cut outputs to files first to combine them later, shown in steps 2 and 3 before step 4.

Visual Quiz - 3 Questions

Look at the execution table, what does col1.txt contain after step 2?

A "c\nf"

B "a,b,c\nd,e,f"

C "a\nd"

D "a\nc"

💡 Hint

Check the 'Output' column for step 2 in the execution_table.

At which step does the paste command run?

A Step 4

B Step 3

C Step 2

D Step 5

💡 Hint

Look for the command 'paste col1.txt col3.txt' in the execution_table.

If we changed '-f3' to '-f2' in step 3, what would col3.txt contain?

A "c\nf"

B "b\ne"

C "a\nd"

D "d\nf"

💡 Hint

The '-f2' option extracts the second column, check original file1.txt content.

Concept Snapshot

cut -d',' -fN file.txt extracts column N using comma as delimiter
paste file1 file2 joins lines side by side with tabs
Use cut to get columns, save to files, then paste to combine
Output shows columns combined line by line
Useful for splitting and merging text data

Full Transcript

This example shows how to use the 'cut' command to extract specific columns from a text file using a delimiter, here a comma. We create a file with two lines of comma-separated values. Then we cut the first and third columns into separate files. Finally, we use 'paste' to join these two files side by side, producing combined output. The execution table traces each step, showing file contents and command outputs. Key moments clarify why options like '-d' and '-f' are used with cut, and how paste combines files line by line. The visual quiz tests understanding of file contents after each step and the effect of changing cut options. The snapshot summarizes the commands and their purpose for quick reference.