74 lines
1.6 KiB
Markdown
74 lines
1.6 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 can also be
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used to parse strings or files that are redirected to it (with `<` and `<<`) or
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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.
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You can use IFS to parse by other characters and/or
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[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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When we use `read` to gather user input, the script will pause until the input
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is provided.
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```bash
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echo "What is your name?"
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read name
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echo "What is your password?"
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read -s pass
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read
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```
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> If you don't specify variables, `read` will automatically parse using
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> whitespace
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## Example of piping to read
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Here we use [find](/Programming_Languages/Shell/Find.md) to collate the files in
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the current directory and then pipe them 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
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that `read` returns, e.g:
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```bash
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while read line; 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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## $REPLY
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If you do not assign a variable name to store the value that `read` reads a
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default (`$REPLY`) is applied. You can reference this value in your code.
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For example the following loop does something if `$REPLY` is equal to an empty
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string:
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```bash
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while read;
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do
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((count++))
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if [[ -z "$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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