Getting different results running same commands step by step at a terminal and within a script [duplicate]
This question already has an answer here:
New line in bash variables
3 answers
pid=$(pgrep 'engrampa') #Get the PID of the engrampa processes .
killpid=$(echo $pid | head -1) #Get only the first line of the $pid variable and put into a new variable called $killpid.
kill $killpid
I want to maintain only the first line of the variable $pid.
Let's say I have 3 instances of the engrampa process open.
When I run the commands above step by step at terminal, I get exactly what I want: 2590
https://imgur.com/a/Gf01Icd
When I run those exaclty commands in a script I get this result: 2590 18425 18449
https://imgur.com/a/Zi7HKkG
Why is that happening?
shell-script head pgrep
asked Dec 17 at 23:16
Lucas Rizzini
267
marked as duplicate by muru, Community♦ Dec 18 at 1:12
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
add a comment |
This question already has an answer here:
New line in bash variables
3 answers
pid=$(pgrep 'engrampa') #Get the PID of the engrampa processes .
killpid=$(echo $pid | head -1) #Get only the first line of the $pid variable and put into a new variable called $killpid.
kill $killpid
I want to maintain only the first line of the variable $pid.
Let's say I have 3 instances of the engrampa process open.
When I run the commands above step by step at terminal, I get exactly what I want: 2590
https://imgur.com/a/Gf01Icd
When I run those exaclty commands in a script I get this result: 2590 18425 18449
https://imgur.com/a/Zi7HKkG
Why is that happening?
shell-script head pgrep
asked Dec 17 at 23:16
Lucas Rizzini
267
marked as duplicate by muru, Community♦ Dec 18 at 1:12
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
1
Which shell are you using in the terminal? perhaps it is not word-splitting the unquoted$pid, whereas the non-interactivebashshell is (see for example Why are embedded newlines in command expansion replaced with whitespaces?)
– steeldriver
Dec 17 at 23:43
There is an excellent article on how to do process management at Greg's Wiki.
– l0b0
Dec 18 at 0:12
add a comment |
This question already has an answer here:
New line in bash variables
3 answers
pid=$(pgrep 'engrampa') #Get the PID of the engrampa processes .
killpid=$(echo $pid | head -1) #Get only the first line of the $pid variable and put into a new variable called $killpid.
kill $killpid
I want to maintain only the first line of the variable $pid.
Let's say I have 3 instances of the engrampa process open.
When I run the commands above step by step at terminal, I get exactly what I want: 2590
https://imgur.com/a/Gf01Icd
When I run those exaclty commands in a script I get this result: 2590 18425 18449
https://imgur.com/a/Zi7HKkG
Why is that happening?
shell-script head pgrep
asked Dec 17 at 23:16
Lucas Rizzini
267
This question already has an answer here:
New line in bash variables
3 answers
pid=$(pgrep 'engrampa') #Get the PID of the engrampa processes .
killpid=$(echo $pid | head -1) #Get only the first line of the $pid variable and put into a new variable called $killpid.
kill $killpid
I want to maintain only the first line of the variable $pid.
Let's say I have 3 instances of the engrampa process open.
When I run the commands above step by step at terminal, I get exactly what I want: 2590
https://imgur.com/a/Gf01Icd
When I run those exaclty commands in a script I get this result: 2590 18425 18449
https://imgur.com/a/Zi7HKkG
Why is that happening?
This question already has an answer here:
New line in bash variables
3 answers
shell-script head pgrep
shell-script head pgrep
asked Dec 17 at 23:16
Lucas Rizzini
267
asked Dec 17 at 23:16
Lucas Rizzini
267
edited Dec 18 at 0:26
asked Dec 17 at 23:16
Lucas Rizzini
267
asked Dec 17 at 23:16
Lucas Rizzini
267
asked Dec 17 at 23:16
Lucas Rizzini
267
267
marked as duplicate by muru, Community♦ Dec 18 at 1:12
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
marked as duplicate by muru, Community♦ Dec 18 at 1:12
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
1
Which shell are you using in the terminal? perhaps it is not word-splitting the unquoted$pid, whereas the non-interactivebashshell is (see for example Why are embedded newlines in command expansion replaced with whitespaces?)
– steeldriver
Dec 17 at 23:43
There is an excellent article on how to do process management at Greg's Wiki.
– l0b0
Dec 18 at 0:12
add a comment |
1
Which shell are you using in the terminal? perhaps it is not word-splitting the unquoted$pid, whereas the non-interactivebashshell is (see for example Why are embedded newlines in command expansion replaced with whitespaces?)
– steeldriver
Dec 17 at 23:43
There is an excellent article on how to do process management at Greg's Wiki.
– l0b0
Dec 18 at 0:12
1
1
Which shell are you using in the terminal? perhaps it is not word-splitting the unquoted
$pid, whereas the non-interactive bash shell is (see for example Why are embedded newlines in command expansion replaced with whitespaces?)– steeldriver
Dec 17 at 23:43
Which shell are you using in the terminal? perhaps it is not word-splitting the unquoted
$pid, whereas the non-interactive bash shell is (see for example Why are embedded newlines in command expansion replaced with whitespaces?)– steeldriver
Dec 17 at 23:43
There is an excellent article on how to do process management at Greg's Wiki.
– l0b0
Dec 18 at 0:12
There is an excellent article on how to do process management at Greg's Wiki.
– l0b0
Dec 18 at 0:12
add a comment |
1 Answer
1
active
oldest
votes
Edit: Identified my problem thanks to steeldriver comment.
Running echo $pid | head -1 in bash do nothing. Running the same command at zsh shell I get exactly what I want.
bash shell output -> 2590 18425 18449
zsh shell output -> 2590
That being stated, my problem has been solved changing the shell of the script to #!/bin/zsh.
Edit: Another solution, and more suitable, is just using echo $pid | awk '{print $1}' instead echo $pid | head -1. It works on both shell. Thanks to Christopher comment.
answered Dec 18 at 0:27
Lucas Rizzini
267
Your original version would have worked inbashif you'd quoted the variable:echo "$pid" | head -1. However you might want to consider usingpgrep -norpgrep -o(orpidofwith the-sswitch) so as to avoid piping toheadaltogether.
– steeldriver
Dec 18 at 1:16
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Edit: Identified my problem thanks to steeldriver comment.
Running echo $pid | head -1 in bash do nothing. Running the same command at zsh shell I get exactly what I want.
bash shell output -> 2590 18425 18449
zsh shell output -> 2590
That being stated, my problem has been solved changing the shell of the script to #!/bin/zsh.
Edit: Another solution, and more suitable, is just using echo $pid | awk '{print $1}' instead echo $pid | head -1. It works on both shell. Thanks to Christopher comment.
answered Dec 18 at 0:27
Lucas Rizzini
267
Your original version would have worked inbashif you'd quoted the variable:echo "$pid" | head -1. However you might want to consider usingpgrep -norpgrep -o(orpidofwith the-sswitch) so as to avoid piping toheadaltogether.
– steeldriver
Dec 18 at 1:16
add a comment |
Edit: Identified my problem thanks to steeldriver comment.
Running echo $pid | head -1 in bash do nothing. Running the same command at zsh shell I get exactly what I want.
bash shell output -> 2590 18425 18449
zsh shell output -> 2590
That being stated, my problem has been solved changing the shell of the script to #!/bin/zsh.
Edit: Another solution, and more suitable, is just using echo $pid | awk '{print $1}' instead echo $pid | head -1. It works on both shell. Thanks to Christopher comment.
answered Dec 18 at 0:27
Lucas Rizzini
267
Your original version would have worked inbashif you'd quoted the variable:echo "$pid" | head -1. However you might want to consider usingpgrep -norpgrep -o(orpidofwith the-sswitch) so as to avoid piping toheadaltogether.
– steeldriver
Dec 18 at 1:16
add a comment |
Edit: Identified my problem thanks to steeldriver comment.
Running echo $pid | head -1 in bash do nothing. Running the same command at zsh shell I get exactly what I want.
bash shell output -> 2590 18425 18449
zsh shell output -> 2590
That being stated, my problem has been solved changing the shell of the script to #!/bin/zsh.
Edit: Another solution, and more suitable, is just using echo $pid | awk '{print $1}' instead echo $pid | head -1. It works on both shell. Thanks to Christopher comment.
answered Dec 18 at 0:27
Lucas Rizzini
267
Edit: Identified my problem thanks to steeldriver comment.
Running echo $pid | head -1 in bash do nothing. Running the same command at zsh shell I get exactly what I want.
bash shell output -> 2590 18425 18449
zsh shell output -> 2590
That being stated, my problem has been solved changing the shell of the script to #!/bin/zsh.
Edit: Another solution, and more suitable, is just using echo $pid | awk '{print $1}' instead echo $pid | head -1. It works on both shell. Thanks to Christopher comment.
answered Dec 18 at 0:27
Lucas Rizzini
267
edited Dec 18 at 0:41
answered Dec 18 at 0:27
Lucas Rizzini
267
answered Dec 18 at 0:27
Lucas Rizzini
267
answered Dec 18 at 0:27
Lucas Rizzini
267
267
Your original version would have worked inbashif you'd quoted the variable:echo "$pid" | head -1. However you might want to consider usingpgrep -norpgrep -o(orpidofwith the-sswitch) so as to avoid piping toheadaltogether.
– steeldriver
Dec 18 at 1:16
add a comment |
Your original version would have worked inbashif you'd quoted the variable:echo "$pid" | head -1. However you might want to consider usingpgrep -norpgrep -o(orpidofwith the-sswitch) so as to avoid piping toheadaltogether.
– steeldriver
Dec 18 at 1:16
Your original version would have worked in
bash if you'd quoted the variable: echo "$pid" | head -1. However you might want to consider using pgrep -n or pgrep -o (or pidof with the -s switch) so as to avoid piping to head altogether.– steeldriver
Dec 18 at 1:16
Your original version would have worked in
bash if you'd quoted the variable: echo "$pid" | head -1. However you might want to consider using pgrep -n or pgrep -o (or pidof with the -s switch) so as to avoid piping to head altogether.– steeldriver
Dec 18 at 1:16
add a comment |
1
Which shell are you using in the terminal? perhaps it is not word-splitting the unquoted
$pid, whereas the non-interactivebashshell is (see for example Why are embedded newlines in command expansion replaced with whitespaces?)– steeldriver
Dec 17 at 23:43
There is an excellent article on how to do process management at Greg's Wiki.
– l0b0
Dec 18 at 0:12