mirror of https://github.com/CrimsonTome/tldr.git
30 lines
847 B
Markdown
30 lines
847 B
Markdown
# if
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> Simple shell conditional.
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> See also: `test`, `[`.
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> More information: <https://www.tcl.tk/man/tcl8.6.11/TclCmd/if.html>.
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- Execute two different commands based on a condition:
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`if {{command}}; then {{echo "true"}}; else {{echo "false"}}; fi`
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- Check if a variable is defined:
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`if [[ -n "{{$VARIABLE}}" ]]; then {{echo "defined"}}; else {{echo "not defined"}}; fi`
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- Check if a file exists:
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`if [[ -f "{{path/to/file}}" ]]; then {{echo "true"}}; else {{echo "false"}}; fi`
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- Check if a directory exists:
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`if [[ -d "{{path/to/directory}}" ]]; then {{echo "true"}}; else {{echo "false"}}; fi`
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- Check if a file or directory exists:
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`if [[ -e "{{path/to/file_or_directory}}" ]]; then {{echo "true"}}; else {{echo "false"}}; fi`
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- List all possible conditions (`test` is an alias to `[`; both are commonly used with `if`):
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`man [`
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