The reason the code with local returns 0 is because $? “Expands to the exit status of the most recently executed foreground pipeline.” Thus $? is returning the success of local You can fix this behavior by separating the declaration of x from the initialization of x like so: $ fun() { local x; x=$(false); … Read more
Bash has a handy SECONDS builtin variable that tracks the number of seconds that have passed since the shell was started. This variable retains its properties when assigned to, and the value returned after the assignment is the number of seconds since the assignment plus the assigned value. Thus, you can just set SECONDS to … Read more
test (or [ expr ]) is a builtin function. Like all functions in bash, you pass its arguments as whitespace separated words. As the man page for bash builtins states: “Each operator and operand must be a separate argument.” It’s just the way bash and most other Unix shells work. Variable assignment is different. In … Read more
I think finding file isn’t the difficult part for you. I therefore just go to the point, to do the +1 calculation. If you have gnu sed, it could be done in this way: sed -r ‘s/(.*)(\?cache_version=)([0-9]+)(.*)/echo “\1\2$((\3+1))\4″/ge’ file let’s take an example: kent$ cat test ello barbaz?cache_version=3fooooo bye kent$ sed -r ‘s/(.*)(\?cache_version=)([0-9]+)(.*)/echo “\1\2$((\3+1))\4″/ge’ test … Read more
As other people explained, getopts doesn’t parse long options. You can use getopt, but it’s not portable (and it is broken on some platform…) As a workaround, you can implement a shell loop. Here an example that transforms long options to short ones before using the standard getopts command (it’s simpler in my opinion): # … Read more
shell parsing is useful only for integer division: var1=8 var2=4 echo $((var1 / var2)) output: 2 instead your example: var1=3 var2=4 echo $((var1 / var2)) ouput: 0 it’s better to use bc: echo “scale=2 ; $var1 / $var2” | bc output: .75 scale is the precision required
The correct options are (in increasing order of recommendation): # Single POSIX test command with -o operator (not recommended anymore). # Quotes strongly recommended to guard against empty or undefined variables. while [ “$stats” -gt 300 -o “$stats” -eq 0 ] # Two POSIX test commands joined in a list with ||. # Quotes strongly … Read more
You want to use “[email protected]” (quoted dollar at) to pass parameters to a subscript. Like so …. ls-color.sh: #!/bin/bash /bin/ls –color=auto “[email protected]” # passes though all CLI-args to ‘ls’ As to why….. From the Bash man page: $* — Expands to the positional parameters, starting from one. When the expansion occurs within double quotes, it … Read more
What you could do, is register the top level shell for the TERM signal to exit, and then send a TERM to the top level shell: #!/bin/bash trap “exit 1” TERM export TOP_PID=$$ function func() { echo “Goodbye” kill -s TERM $TOP_PID } echo “Function call will abort” echo $(func) echo “This will never be … Read more
Great question. I use a pattern like this for most of my scripts: #!/bin/bash main() { foo bar baz } foo() { } bar() { } baz() { } main “[email protected]” You can read the code from top to bottom, but it doesn’t actually start executing until the last line. By passing “[email protected]” to main() … Read more