58 lines
1.5 KiB
Markdown
58 lines
1.5 KiB
Markdown
---
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categories:
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- Programming Languages
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tags:
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- shell
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---
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# read
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The primary use of `read` is to capture user input from `stdin`. It is also often used frequently to parse strings or files that are redirected to it (with `<` and `<<`) or piped to it. In each case, what is read is stored as a variable.
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`read` will parse line by line using a space (`\n`) as the default delimiter. You can use IFS to parse by other characters and/or [split the contents into an array](/Programming_Languages/Shell/Split_into_array.md).
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## Example of capturing user input
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```bash
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$ read var1 var2
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$ thomas bishop # user inputs this
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$ echo $var2
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$ bishop
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```
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> If you don't specify variables, `read` will automatically parse using whitespace
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## Example of piping to `read`
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This reads the files in a directory and passes the file names to `read`.
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```bash
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find -type -f -not -path "./.git/" | read $fname
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```
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## Example of parsing a file
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We will typically read from a source and then do something with each variable that `read` returns, e.g:
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```bash
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while read var; do
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if [var == 'something']; then
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# do something
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done < './input-file.txt
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```
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## $REPLY
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If you do not assign a variable name to store the value that `read` reads a default (`$REPLY`) is applied. You can reference this value in your code.
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For example the following loop does something if `$REPLY` is equal to an empty string:
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```bash
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while read;
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do
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((count++))
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if [[ -z "$REPLY" ]]; then
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echo "$count"
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fi
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done < "$input
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```
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