awk:awk_fields
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| Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
| awk:awk_fields [2020/05/04 23:05] – peter | awk:awk_fields [2022/06/13 09:37] (current) – peter | ||
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| ====== AWK - AWK Fields ====== | ====== AWK - AWK Fields ====== | ||
| - | |||
| - | ===== Understanding Fields. ===== | ||
| Assuming a file exists with the following contents: | Assuming a file exists with the following contents: | ||
| Line 7: | Line 5: | ||
| < | < | ||
| 10 | 10 | ||
| - | 11 | + | 11 |
| 12 | 12 | ||
| 13 | 13 | ||
| Line 14: | Line 12: | ||
| </ | </ | ||
| - | Issue the following command: | + | ---- |
| + | |||
| + | ===== Understanding Fields ===== | ||
| - | < | + | < |
| awk ' | awk ' | ||
| </ | </ | ||
| - | which will display something like: | + | returns: |
| < | < | ||
| 10 Peter Terence Roux 45 | 10 Peter Terence Roux 45 | ||
| - | 11 Virginia | + | 11 Virginia |
| 12 Felix Devon Roux 5 | 12 Felix Devon Roux 5 | ||
| 13 David Bruce Stevenson 48 | 13 David Bruce Stevenson 48 | ||
| Line 31: | Line 31: | ||
| </ | </ | ||
| - | | + | <WRAP info> |
| + | **NOTE: | ||
| * Each field is split by a field separator, which by default is a space or comma. | * Each field is split by a field separator, which by default is a space or comma. | ||
| * As can be seen, it does not matter how many spaces separate each field in the input file. | * As can be seen, it does not matter how many spaces separate each field in the input file. | ||
| - | <WRAP info> | + | |
| - | **NOTE:** As AWK reads the input, the entire record is assigned to the variable $0. | + | |
| </ | </ | ||
| Line 43: | Line 45: | ||
| ===== Display Only Certain Fields ===== | ===== Display Only Certain Fields ===== | ||
| - | To only print the name and surname, i.e. fields $2 and $4, issue the following command: | + | To only print the name and surname, i.e. fields $2 and $4: |
| - | < | + | < |
| awk ' | awk ' | ||
| </ | </ | ||
| - | which will display something like: | + | returns: |
| < | < | ||
| Line 62: | Line 64: | ||
| The ability to address each field with a unique number allows only specific fields to be output. | The ability to address each field with a unique number allows only specific fields to be output. | ||
| - | **NOTE** : Fields can be printed out in any order, for example: | + | <WRAP info> |
| + | **NOTE** : Fields can be printed out in any order. For example: | ||
| - | < | + | < |
| awk ' | awk ' | ||
| </ | </ | ||
| - | result: | + | returns: |
| < | < | ||
| Line 80: | Line 83: | ||
| Notice that the surname is now printed before first name. | Notice that the surname is now printed before first name. | ||
| + | </ | ||
| ---- | ---- | ||
| Line 85: | Line 89: | ||
| ===== Display Multi-line Output ===== | ===== Display Multi-line Output ===== | ||
| - | To output onto multiple lines, issue the following command: | + | To output onto multiple lines: |
| - | < | + | < |
| awk ' | awk ' | ||
| </ | </ | ||
| - | which will display something like: | + | returns: |
| < | < | ||
| Peter Terence Roux | Peter Terence Roux | ||
| 10 45 | 10 45 | ||
| - | Virginia | + | Virginia |
| 11 45 | 11 45 | ||
| Felix Devon Roux | Felix Devon Roux | ||
| Line 108: | Line 112: | ||
| </ | </ | ||
| - | The semicolon (;) indicates to write some data to a different line. | + | <WRAP info> |
| + | **NOTE: | ||
| + | </ | ||
| This could also be written as the following, which will produce the same results: | This could also be written as the following, which will produce the same results: | ||
| - | < | + | < |
| awk ' | awk ' | ||
| </ | </ | ||
awk/awk_fields.1588633530.txt.gz · Last modified: 2020/07/15 09:30 (external edit)