Bash Expressions: Difference between revisions
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{{External|http://mywiki.wooledge.org/BashFAQ/031}} | {{External|http://mywiki.wooledge.org/BashFAQ/031}} | ||
[ and "test" are equivalent. [[]] is a keyword rather than a | [ and "test" are equivalent. [[]] is a keyword rather than a program. | ||
Revision as of 19:50, 20 February 2018
Internal
Conditional Expressions
Difference between -a and &&
If want to combine the results of multiple command executions in an if condition, use &&, not -a.
Example:
if grep "something" /file1.txt && grep "something" /file2.txt' then
# "something" exists in both files ...
fi
-a should be used in test expressions:
if [ -f /file.txt -a -x /file.txt ]; then ... fi
[[...]]
[ and "test" are equivalent. [[]] is a keyword rather than a program.