Run another command before running the command the user wants to run
Let's say I want to modify the original behavior of the ls tool this way:
$ ls
Hello World
file1 file2 ...
How can I do this?
When running ls I would like to run another command let's say echo "Hello World!".
The quick solution I see is using alias:
alias orig_ls="ls"
alias ls='echo "Hello World!"'
However, this is not a real solution since when I will run orig_ls it will output "Hello World!".
bash shell command-line alias
asked Jan 25 '15 at 14:33
Ionică BizăuIonică Bizău
1,16752040
add a comment |
Let's say I want to modify the original behavior of the ls tool this way:
$ ls
Hello World
file1 file2 ...
How can I do this?
When running ls I would like to run another command let's say echo "Hello World!".
The quick solution I see is using alias:
alias orig_ls="ls"
alias ls='echo "Hello World!"'
However, this is not a real solution since when I will run orig_ls it will output "Hello World!".
bash shell command-line alias
asked Jan 25 '15 at 14:33
Ionică BizăuIonică Bizău
1,16752040
Put another ls in the users own path and use this to hook the original.
– peterh
Jan 25 '15 at 14:38
add a comment |
Let's say I want to modify the original behavior of the ls tool this way:
$ ls
Hello World
file1 file2 ...
How can I do this?
When running ls I would like to run another command let's say echo "Hello World!".
The quick solution I see is using alias:
alias orig_ls="ls"
alias ls='echo "Hello World!"'
However, this is not a real solution since when I will run orig_ls it will output "Hello World!".
bash shell command-line alias
asked Jan 25 '15 at 14:33
Ionică BizăuIonică Bizău
1,16752040
Let's say I want to modify the original behavior of the ls tool this way:
$ ls
Hello World
file1 file2 ...
How can I do this?
When running ls I would like to run another command let's say echo "Hello World!".
The quick solution I see is using alias:
alias orig_ls="ls"
alias ls='echo "Hello World!"'
However, this is not a real solution since when I will run orig_ls it will output "Hello World!".
bash shell command-line alias
bash shell command-line alias
asked Jan 25 '15 at 14:33
Ionică BizăuIonică Bizău
1,16752040
asked Jan 25 '15 at 14:33
Ionică BizăuIonică Bizău
1,16752040
asked Jan 25 '15 at 14:33
Ionică BizăuIonică Bizău
1,16752040
asked Jan 25 '15 at 14:33
Ionică BizăuIonică Bizău
1,16752040
asked Jan 25 '15 at 14:33
Ionică BizăuIonică Bizău
1,16752040
1,16752040
Put another ls in the users own path and use this to hook the original.
– peterh
Jan 25 '15 at 14:38
add a comment |
Put another ls in the users own path and use this to hook the original.
– peterh
Jan 25 '15 at 14:38
Put another ls in the users own path and use this to hook the original.
– peterh
Jan 25 '15 at 14:38
Put another ls in the users own path and use this to hook the original.
– peterh
Jan 25 '15 at 14:38
add a comment |
2 Answers
2
active
oldest
votes
Sometimes an alias isn't powerful enough to easily do what you want, so here's a way without using them.
In some file that is sourced when your shell starts (e.g. .bashrc), add the following function:
ls () {
echo "Hello world!"
command ls "$@"
}
Unlike an alias, a function can recurse. That's why command ls is used instead of ls; it tells your shell to use the actual ls instead of the function you've just defined.
edited Jan 9 at 23:02
Gilles
532k12810661592
answered Jan 26 '15 at 0:44
undergroundmonorailundergroundmonorail
701613
2
Indeed. This solution scales better. +1
– PythonNut
Jan 26 '15 at 0:57
Indeed! This is a lot better. Thanks!
– Ionică Bizău
Jan 26 '15 at 7:43
What is thecommandalternative for OS X?
– Ionică Bizău
Feb 9 '15 at 16:21
@IonicăBizău I have no ideacommanddidn't work :/ I have no idea and I don't have a Mac with which to test it, sorry.
– undergroundmonorail
Feb 9 '15 at 16:25
add a comment |
You must not forget to call ls:
alias ls='echo "Hello World!"; ls'
answered Jan 25 '15 at 14:38
Hauke LagingHauke Laging
56.2k1285135
Ha! I supposed this will create an infinite cycle! But why doesn't it create an infinite loop?
– Ionică Bizău
Jan 25 '15 at 16:58
1
You might instead try alias ls 'echo "Hello World!"; /usr/bin/ls'
– jamesqf
Jan 25 '15 at 18:19
5
@IonicăBizău any given "alias expansion rule" is only used once.
– David Z
Jan 25 '15 at 19:53
Would joining the two with an & also work? That would also ensure that the user's command is only run if the custom one works, right?
– Nic Hartley
Jan 25 '15 at 20:42
@QPaysTaxes You can use&indeed but I don't get the argument you make from that.
– Hauke Laging
Jan 26 '15 at 1:02
|
show 2 more comments
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Sometimes an alias isn't powerful enough to easily do what you want, so here's a way without using them.
In some file that is sourced when your shell starts (e.g. .bashrc), add the following function:
ls () {
echo "Hello world!"
command ls "$@"
}
Unlike an alias, a function can recurse. That's why command ls is used instead of ls; it tells your shell to use the actual ls instead of the function you've just defined.
edited Jan 9 at 23:02
Gilles
532k12810661592
answered Jan 26 '15 at 0:44
undergroundmonorailundergroundmonorail
701613
2
Indeed. This solution scales better. +1
– PythonNut
Jan 26 '15 at 0:57
Indeed! This is a lot better. Thanks!
– Ionică Bizău
Jan 26 '15 at 7:43
What is thecommandalternative for OS X?
– Ionică Bizău
Feb 9 '15 at 16:21
@IonicăBizău I have no ideacommanddidn't work :/ I have no idea and I don't have a Mac with which to test it, sorry.
– undergroundmonorail
Feb 9 '15 at 16:25
add a comment |
Sometimes an alias isn't powerful enough to easily do what you want, so here's a way without using them.
In some file that is sourced when your shell starts (e.g. .bashrc), add the following function:
ls () {
echo "Hello world!"
command ls "$@"
}
Unlike an alias, a function can recurse. That's why command ls is used instead of ls; it tells your shell to use the actual ls instead of the function you've just defined.
edited Jan 9 at 23:02
Gilles
532k12810661592
answered Jan 26 '15 at 0:44
undergroundmonorailundergroundmonorail
701613
2
Indeed. This solution scales better. +1
– PythonNut
Jan 26 '15 at 0:57
Indeed! This is a lot better. Thanks!
– Ionică Bizău
Jan 26 '15 at 7:43
What is thecommandalternative for OS X?
– Ionică Bizău
Feb 9 '15 at 16:21
@IonicăBizău I have no ideacommanddidn't work :/ I have no idea and I don't have a Mac with which to test it, sorry.
– undergroundmonorail
Feb 9 '15 at 16:25
add a comment |
Sometimes an alias isn't powerful enough to easily do what you want, so here's a way without using them.
In some file that is sourced when your shell starts (e.g. .bashrc), add the following function:
ls () {
echo "Hello world!"
command ls "$@"
}
Unlike an alias, a function can recurse. That's why command ls is used instead of ls; it tells your shell to use the actual ls instead of the function you've just defined.
edited Jan 9 at 23:02
Gilles
532k12810661592
answered Jan 26 '15 at 0:44
undergroundmonorailundergroundmonorail
701613
Sometimes an alias isn't powerful enough to easily do what you want, so here's a way without using them.
In some file that is sourced when your shell starts (e.g. .bashrc), add the following function:
ls () {
echo "Hello world!"
command ls "$@"
}
Unlike an alias, a function can recurse. That's why command ls is used instead of ls; it tells your shell to use the actual ls instead of the function you've just defined.
edited Jan 9 at 23:02
Gilles
532k12810661592
answered Jan 26 '15 at 0:44
undergroundmonorailundergroundmonorail
701613
edited Jan 9 at 23:02
Gilles
532k12810661592
edited Jan 9 at 23:02
Gilles
532k12810661592
edited Jan 9 at 23:02
Gilles
532k12810661592
532k12810661592
answered Jan 26 '15 at 0:44
undergroundmonorailundergroundmonorail
701613
answered Jan 26 '15 at 0:44
undergroundmonorailundergroundmonorail
701613
answered Jan 26 '15 at 0:44
undergroundmonorailundergroundmonorail
701613
701613
2
Indeed. This solution scales better. +1
– PythonNut
Jan 26 '15 at 0:57
Indeed! This is a lot better. Thanks!
– Ionică Bizău
Jan 26 '15 at 7:43
What is thecommandalternative for OS X?
– Ionică Bizău
Feb 9 '15 at 16:21
@IonicăBizău I have no ideacommanddidn't work :/ I have no idea and I don't have a Mac with which to test it, sorry.
– undergroundmonorail
Feb 9 '15 at 16:25
add a comment |
2
Indeed. This solution scales better. +1
– PythonNut
Jan 26 '15 at 0:57
Indeed! This is a lot better. Thanks!
– Ionică Bizău
Jan 26 '15 at 7:43
What is thecommandalternative for OS X?
– Ionică Bizău
Feb 9 '15 at 16:21
@IonicăBizău I have no ideacommanddidn't work :/ I have no idea and I don't have a Mac with which to test it, sorry.
– undergroundmonorail
Feb 9 '15 at 16:25
2
2
Indeed. This solution scales better. +1
– PythonNut
Jan 26 '15 at 0:57
Indeed. This solution scales better. +1
– PythonNut
Jan 26 '15 at 0:57
Indeed! This is a lot better. Thanks!
– Ionică Bizău
Jan 26 '15 at 7:43
Indeed! This is a lot better. Thanks!
– Ionică Bizău
Jan 26 '15 at 7:43
What is the
command alternative for OS X?– Ionică Bizău
Feb 9 '15 at 16:21
What is the
command alternative for OS X?– Ionică Bizău
Feb 9 '15 at 16:21
@IonicăBizău I have no idea
command didn't work :/ I have no idea and I don't have a Mac with which to test it, sorry.– undergroundmonorail
Feb 9 '15 at 16:25
@IonicăBizău I have no idea
command didn't work :/ I have no idea and I don't have a Mac with which to test it, sorry.– undergroundmonorail
Feb 9 '15 at 16:25
add a comment |
You must not forget to call ls:
alias ls='echo "Hello World!"; ls'
answered Jan 25 '15 at 14:38
Hauke LagingHauke Laging
56.2k1285135
Ha! I supposed this will create an infinite cycle! But why doesn't it create an infinite loop?
– Ionică Bizău
Jan 25 '15 at 16:58
1
You might instead try alias ls 'echo "Hello World!"; /usr/bin/ls'
– jamesqf
Jan 25 '15 at 18:19
5
@IonicăBizău any given "alias expansion rule" is only used once.
– David Z
Jan 25 '15 at 19:53
Would joining the two with an & also work? That would also ensure that the user's command is only run if the custom one works, right?
– Nic Hartley
Jan 25 '15 at 20:42
@QPaysTaxes You can use&indeed but I don't get the argument you make from that.
– Hauke Laging
Jan 26 '15 at 1:02
|
show 2 more comments
You must not forget to call ls:
alias ls='echo "Hello World!"; ls'
answered Jan 25 '15 at 14:38
Hauke LagingHauke Laging
56.2k1285135
Ha! I supposed this will create an infinite cycle! But why doesn't it create an infinite loop?
– Ionică Bizău
Jan 25 '15 at 16:58
1
You might instead try alias ls 'echo "Hello World!"; /usr/bin/ls'
– jamesqf
Jan 25 '15 at 18:19
5
@IonicăBizău any given "alias expansion rule" is only used once.
– David Z
Jan 25 '15 at 19:53
Would joining the two with an & also work? That would also ensure that the user's command is only run if the custom one works, right?
– Nic Hartley
Jan 25 '15 at 20:42
@QPaysTaxes You can use&indeed but I don't get the argument you make from that.
– Hauke Laging
Jan 26 '15 at 1:02
|
show 2 more comments
You must not forget to call ls:
alias ls='echo "Hello World!"; ls'
answered Jan 25 '15 at 14:38
Hauke LagingHauke Laging
56.2k1285135
You must not forget to call ls:
alias ls='echo "Hello World!"; ls'
answered Jan 25 '15 at 14:38
Hauke LagingHauke Laging
56.2k1285135
answered Jan 25 '15 at 14:38
Hauke LagingHauke Laging
56.2k1285135
answered Jan 25 '15 at 14:38
Hauke LagingHauke Laging
56.2k1285135
answered Jan 25 '15 at 14:38
Hauke LagingHauke Laging
56.2k1285135
56.2k1285135
Ha! I supposed this will create an infinite cycle! But why doesn't it create an infinite loop?
– Ionică Bizău
Jan 25 '15 at 16:58
1
You might instead try alias ls 'echo "Hello World!"; /usr/bin/ls'
– jamesqf
Jan 25 '15 at 18:19
5
@IonicăBizău any given "alias expansion rule" is only used once.
– David Z
Jan 25 '15 at 19:53
Would joining the two with an & also work? That would also ensure that the user's command is only run if the custom one works, right?
– Nic Hartley
Jan 25 '15 at 20:42
@QPaysTaxes You can use&indeed but I don't get the argument you make from that.
– Hauke Laging
Jan 26 '15 at 1:02
|
show 2 more comments
Ha! I supposed this will create an infinite cycle! But why doesn't it create an infinite loop?
– Ionică Bizău
Jan 25 '15 at 16:58
1
You might instead try alias ls 'echo "Hello World!"; /usr/bin/ls'
– jamesqf
Jan 25 '15 at 18:19
5
@IonicăBizău any given "alias expansion rule" is only used once.
– David Z
Jan 25 '15 at 19:53
Would joining the two with an & also work? That would also ensure that the user's command is only run if the custom one works, right?
– Nic Hartley
Jan 25 '15 at 20:42
@QPaysTaxes You can use&indeed but I don't get the argument you make from that.
– Hauke Laging
Jan 26 '15 at 1:02
Ha! I supposed this will create an infinite cycle! But why doesn't it create an infinite loop?
– Ionică Bizău
Jan 25 '15 at 16:58
Ha! I supposed this will create an infinite cycle! But why doesn't it create an infinite loop?
– Ionică Bizău
Jan 25 '15 at 16:58
1
1
You might instead try alias ls 'echo "Hello World!"; /usr/bin/ls'
– jamesqf
Jan 25 '15 at 18:19
You might instead try alias ls 'echo "Hello World!"; /usr/bin/ls'
– jamesqf
Jan 25 '15 at 18:19
5
5
@IonicăBizău any given "alias expansion rule" is only used once.
– David Z
Jan 25 '15 at 19:53
@IonicăBizău any given "alias expansion rule" is only used once.
– David Z
Jan 25 '15 at 19:53
Would joining the two with an & also work? That would also ensure that the user's command is only run if the custom one works, right?
– Nic Hartley
Jan 25 '15 at 20:42
Would joining the two with an & also work? That would also ensure that the user's command is only run if the custom one works, right?
– Nic Hartley
Jan 25 '15 at 20:42
@QPaysTaxes You can use
& indeed but I don't get the argument you make from that.– Hauke Laging
Jan 26 '15 at 1:02
@QPaysTaxes You can use
& indeed but I don't get the argument you make from that.– Hauke Laging
Jan 26 '15 at 1:02
|
show 2 more comments
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Put another ls in the users own path and use this to hook the original.
– peterh
Jan 25 '15 at 14:38