Difference between revisions of "Awk"
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| − | It's usually a better idea to use one command instead of using a [[pipe]] to another command, where possible. A common mistake | + | It's usually a better idea to use one command instead of using a [[pipe]] to another command, where possible. A common mistake: |
# grep root /etc/passwd | awk -F: '{print $7}' | # grep root /etc/passwd | awk -F: '{print $7}' | ||
/bin/bash | /bin/bash | ||
| − | which | + | which can be easily done all in awk: |
# awk -F: '/root/ {print $7}' /etc/passwd | # awk -F: '/root/ {print $7}' /etc/passwd | ||
/bin/bash | /bin/bash | ||
| − | + | Say you wanted to find out how much resident memory [[xfce4]] was using on your system, and it appears most xfce applications start with "xf": | |
$ ps auwx | awk '/xf/{print $5}' | $ ps auwx | awk '/xf/{print $5}' | ||
15924 | 15924 | ||
| Line 19: | Line 19: | ||
| − | + | If you wanted to use awk to add the results together instead of doing it manually: | |
$ ps auwx | awk '/xf/{ tot += $5 } END { print tot }' | $ ps auwx | awk '/xf/{ tot += $5 } END { print tot }' | ||
69108 | 69108 | ||
''N.B.'' This can be misleading in the case of programs that use large amounts of shared memory (like java). | ''N.B.'' This can be misleading in the case of programs that use large amounts of shared memory (like java). | ||
Revision as of 19:29, 15 March 2006
It's usually a better idea to use one command instead of using a pipe to another command, where possible. A common mistake:
# grep root /etc/passwd | awk -F: '{print $7}'
/bin/bash
which can be easily done all in awk:
# awk -F: '/root/ {print $7}' /etc/passwd
/bin/bash
Say you wanted to find out how much resident memory xfce4 was using on your system, and it appears most xfce applications start with "xf":
$ ps auwx | awk '/xf/{print $5}'
15924
14668
11948
11764
12944
16264
1860
If you wanted to use awk to add the results together instead of doing it manually:
$ ps auwx | awk '/xf/{ tot += $5 } END { print tot }'
69108
N.B. This can be misleading in the case of programs that use large amounts of shared memory (like java).
