Bash Expressions: Difference between revisions
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(Created page with "=Internal= * bash =Difference between <tt>-a</tt> and <tt>&&</tt>= If want to combine the results of multiple command executions in an <tt>if</tt> conditi...") |
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=Difference between <tt>-a</tt> and <tt>&&</tt>= | =Difference between <tt>-a</tt> and <tt>&&</tt>= | ||
If want to combine the results of multiple command executions in an <tt>if</tt> condition, use <tt>&&</ | If want to combine the results of multiple command executions in an <tt>if</tt> condition, use <tt>&&</tt>, not <tt>-a</tt>. | ||
Example: | Example: | ||
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if grep "something" /file1.txt && grep "something" /file2.txt' then | if grep "something" /file1.txt && grep "something" /file2.txt' then | ||
# "something" exists in both files ... | # "something" exists in both files ... | ||
fi | |||
</pre> | |||
<tt>-a</tt> should be used in <tt>test</tt> expressions: | |||
<pre> | |||
if [ -f /file.txt -a -x /file.txt ]; then | |||
... | |||
fi | fi | ||
</pre> | </pre> | ||
Revision as of 02:25, 28 May 2016
Internal
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