Last updated on November 25, 2020 by Dan Nanni
When you are writing a shell script, there are cases where you need to compare two version numbers, and proceed differently depending on whether one version number is higher/lower than the other. For example, you want to check for the minimum version requirement (i.e., $version ≥ 1.3.0). Or you want to write a conditional statement where the condition is defined by a specific range of version numbers (e.g., 1.0.0 ≤ $version ≤ 2.3.1).
If you want to compare two strings in version format (i.e., "X.Y.Z") in a shell script, one easy way is to use sort
command. With -V
option, the sort
command can sort version numbers within text (in an increasing order by default). With -rV
option, it can sort version numbers in a decreasing order.
Now let's see how we can use the sort
command to compare version numbers in a shell script.
For version number string comparison, the following function definitions come in handy. Note that these functions use the sort
command.
function version_gt() { test "$(echo "[email protected]" | tr " " "n" | sort -V | head -n 1)" != "$1"; } function version_le() { test "$(echo "[email protected]" | tr " " "n" | sort -V | head -n 1)" == "$1"; } function version_lt() { test "$(echo "[email protected]" | tr " " "n" | sort -rV | head -n 1)" != "$1"; } function version_ge() { test "$(echo "[email protected]" | tr " " "n" | sort -rV | head -n 1)" == "$1"; }
These functions perform, respectively, "greater-than", "less than or equal to", "less than", and "greater than or equal to" operations against two specified version numbers. You will need to use bash
shell due to function definitions.
Below is an example bash script that compares two version numbers.
#!/bin/bash VERSION=$1 VERSION2=$2 function version_gt() { test "$(echo "[email protected]" | tr " " "n" | sort -V | head -n 1)" != "$1"; } function version_le() { test "$(echo "[email protected]" | tr " " "n" | sort -V | head -n 1)" == "$1"; } function version_lt() { test "$(echo "[email protected]" | tr " " "n" | sort -rV | head -n 1)" != "$1"; } function version_ge() { test "$(echo "[email protected]" | tr " " "n" | sort -rV | head -n 1)" == "$1"; } if version_gt $VERSION $VERSION2; then echo "$VERSION is greater than $VERSION2" fi if version_le $VERSION $VERSION2; then echo "$VERSION is less than or equal to $VERSION2" fi if version_lt $VERSION $VERSION2; then echo "$VERSION is less than $VERSION2" fi if version_ge $VERSION $VERSION2; then echo "$VERSION is greater than or equal to $VERSION2" fi
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