subshell

This question is not cygwin specific. However, in the cygwin mail archive https://cygwin.com/ml/cygwin-announce/2010-08/msg00015.html are various instructions for setting the cygwin specific igncr shellopt variable and one of them is the instruction: 4a. For a single affected script, add this line just after the she-bang: ~ (set -o igncr) 2>/dev/null && set -o igncr; # comment is needed I understand that set -o igncr sets igncr in SHELLOPTS. However, I do not understand why the instruction also includes invoking it in a subshell. From what I understand, the variables and environment of the

I'm trying to limit the amount of subshells that are spawned in a script that I'm using to sniff our internal network to audit Linux servers in our network. The script works as intended, but due to the way I'm nesting the for loop, it spawns 255 Sub Shells for each network, so therefore it kills the CPU due to the fact that there are over 1000 processes spawned off. I need to be able to limit the amount of processes, and since variables lose their value when in a Sub Shell, I can't figure out a way to make this work. Again, the script works, it just spawns a ton a processes - I need to limit

Here is minimal code for issue demonstration: http://pastebin.com/5TXDpSh5 #!/bin/bash set -e set -o pipefail function echoTraps() { echo "= on start:" trap -p trap -- 'echo func-EXIT' EXIT echo "= after set new:" trap -p # we can ensure after script done - file '/tmp/tmp.txt' was not created trap -- 'echo SIG 1>/tmp/tmp.txt' SIGPIPE SIGHUP SIGINT SIGQUIT SIGTERM } trap -- 'echo main-EXIT1' EXIT echo "===== subshell trap" ( echoTraps; ) echo "===== pipe trap" echoTraps | cat echo "===== done everything" output ===== subshell trap = on start: = after set new: trap -- 'echo func-EXIT' EXIT func

A contrived example... given FOO="/foo/bar/baz" this works (in bash) BAR=$(basename $FOO) # result is BAR="baz" BAZ=${BAR:0:1} # result is BAZ="b" this doesn't BAZ=${$(basename $FOO):0:1} # result is bad substitution My question is which rule causes this [subshell substitution] to evaluate incorrectly? And what is the correct way, if any, to do this in 1 hop? First off, note that when you say this: BAR=$(basename $FOO) # result is BAR="baz" BAZ=${BAR:0:1} # result is BAZ="b" the first bit in the construct for BAZ is BAR and not the value that you want to take the first character of. So even if

I have a bash script start.sh which looks like this: for thing in foo bar; do { background_processor $thing cleanup_on_exit $thing } & done This does what I want: I run start.sh, it exits with code 0, and the two subshells run in the background. Each subshell runs background_processor , and when that exits, it runs cleanup_on_exit . This works even if I exit the terminal from which I originally ran start.sh (even if that was an ssh connection). Then I tried this: ssh user@host "start.sh" This works, except that after start.sh has exited, ssh apparently also waits for the subshells to exit. I

When I execute git branch on the command line I get a list of all the branches on a repo, however when I execute $(git branch) in a sub-shell, it first prints out a list of files in the top level folder in a repo before printing out the branch names. Why? I'm basically trying to iterate over the branches using a for loop, but the listing of files breaks my script. for i in $(git branch); do echo $i done $ git branch * master Try echo * master in your shell and see what you get? Hint: You'll get the list of files in the current directory from the shell glob expansion of * . See