Linux命令——pgrep

参考：Linux pgrep Command Tutorial for Beginners (10 Examples)

Linux命令——ps、pstree

bash基础——grep、基本正则表达式、扩展正则表达式、fgrep

简介

这个命令也是用来查看进程(或线程）信息的。可以理解成是ps+grep

举例

根据用户ID，用户名查找进程(或线程)

使用-u参数。

这一点要称赞pgrep，不像ps（-u接uid，-U接username），-u可以包含uid和username两种情况

[root@localhost lib]# pgrep -u  -d:
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
[root@localhost lib]# pgrep -u root -d:
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

ps的-G好很多，可以接gid和groupname

自定义分隔符

上面的例子我使用了-d参数，这个就是用来自定义分隔符的，默认是换行符，所以默认情况的输出会很多行，如下

[root@localhost lib]# pgrep -u root 

为了输出美观，第一个例子我更改了分隔符

显示进程（或线程）名字

上面那个例子，虽然把root的进程（或线程）都找到了，但是只有ID，太不方便了。

使用-l参数，可以把进程（或线程）名字显示出来。

[root@localhost lib]# pgrep -u root -l
 systemd
 kthreadd
 ksoftirqd/
 kworker/:0H
 migration/
 rcu_bh
 rcu_sched
 lru-add-drain
 watchdog/
 watchdog/
 migration/
 ksoftirqd/
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:
 kworker/:0H
 kdevtmpfs
 netns
 khungtaskd
 writeback
 kintegrityd
 bioset
 kblockd
 md
 edac-poller
 kworker/:
 kswapd0
 ksmd
 khugepaged
 crypto
 kthrotld
 kworker/u256:
 kmpath_rdacd
 kaluad
 kpsmoused
 kworker/:
 ipv6_addrconf
 deferwq
 kworker/:
 kauditd
 kworker/:
 ata_sff
 mpt_poll_0
 mpt/
 scsi_eh_0
 scsi_tmf_0
 kworker/u256:
 scsi_eh_1
 scsi_tmf_1
 scsi_eh_2
 scsi_tmf_2
 ttm_swap
 irq/-vmwgfx
 kworker/:
 kworker/:
 kworker/:
 kdmflush
 bioset
 kdmflush
 bioset
 bioset
 xfsalloc
 xfs_mru_cache
 xfs-buf/dm-
 xfs-data/dm-
 xfs-conv/dm-
 xfs-cil/dm-
 xfs-reclaim/dm-
 xfs-log/dm-
 xfs-eofblocks/d
 xfsaild/dm-
 kworker/:1H
 systemd-journal
 lvmetad
 systemd-udevd
 nfit
 kworker/:
 kvm-irqfd-clean
 xfs-buf/sda1
 xfs-data/sda1
 xfs-conv/sda1
 xfs-cil/sda1
 xfs-reclaim/sda
 xfs-log/sda1
 xfs-eofblocks/s
 xfsaild/sda1
 kdmflush
 bioset
 kworker/:
 xfs-buf/dm-
 xfs-data/dm-
 xfs-conv/dm-
 xfs-cil/dm-
 xfs-reclaim/dm-
 xfs-log/dm-
 xfs-eofblocks/d
 xfsaild/dm-
 auditd
 systemd-logind
 irqbalance
 crond
 ksmtuned
 login
 kworker/:1H
 kworker/:1H
 dhclient
 rsyslogd
 tuned
 sshd
 kworker/:
 master
 kworker/:1H
 bash
 kworker/:1H
 kworker/:1H
 sshd
 bash
 kworker/:1H
 kworker/:1H
 kworker/:
 kworker/:
 kworker/:
 kworker/:
 kworker/:
 sleep

显示命令行命

使用-a参数还可以把这个进程（或线程）启动时的命令行显示出来

pstree也是使用-a显式命令行

[root@localhost lib]# pgrep -u root -a
 /usr/lib/systemd/systemd --switched-root --system --deserialize
 kthreadd
 ksoftirqd/
 kworker/:0H
 migration/
 rcu_bh
 rcu_sched
 lru-add-drain
 watchdog/
 watchdog/
 migration/
 ksoftirqd/
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:
 kworker/:0H
 watchdog/
 migration/
 ksoftirqd/
 kworker/:
 kworker/:0H
 kdevtmpfs
 netns
 khungtaskd
 writeback
 kintegrityd
 bioset
 kblockd
 md
 edac-poller
 kworker/:
 kswapd0
 ksmd
 khugepaged
 crypto
 kthrotld
 kworker/u256:
 kmpath_rdacd
 kaluad
 kpsmoused
 kworker/:
 ipv6_addrconf
 deferwq
 kworker/:
 kauditd
 kworker/:
 ata_sff
 mpt_poll_0
 mpt/
 scsi_eh_0
 scsi_tmf_0
 kworker/u256:
 scsi_eh_1
 scsi_tmf_1
 scsi_eh_2
 scsi_tmf_2
 ttm_swap
 irq/-vmwgfx
 kworker/:
 kworker/:
 kworker/:
 kdmflush
 bioset
 kdmflush
 bioset
 bioset
 xfsalloc
 xfs_mru_cache
 xfs-buf/dm-
 xfs-data/dm-
 xfs-conv/dm-
 xfs-cil/dm-
 xfs-reclaim/dm-
 xfs-log/dm-
 xfs-eofblocks/d
 xfsaild/dm-
 kworker/:1H
 /usr/lib/systemd/systemd-journald
 /usr/sbin/lvmetad -f
 /usr/lib/systemd/systemd-udevd
 nfit
 kworker/:
 kvm-irqfd-clean
 xfs-buf/sda1
 xfs-data/sda1
 xfs-conv/sda1
 xfs-cil/sda1
 xfs-reclaim/sda
 xfs-log/sda1
 xfs-eofblocks/s
 xfsaild/sda1
 kdmflush
 bioset
 kworker/:
 xfs-buf/dm-
 xfs-data/dm-
 xfs-conv/dm-
 xfs-cil/dm-
 xfs-reclaim/dm-
 xfs-log/dm-
 xfs-eofblocks/d
 xfsaild/dm-
 /sbin/auditd
 /usr/lib/systemd/systemd-logind
 /usr/sbin/irqbalance --foreground
 /usr/sbin/crond -n
 /bin/bash /usr/sbin/ksmtuned
 login -- root
 kworker/:1H
 kworker/:1H
 /sbin/dhclient - -q -lf /var/lib/dhclient/dhclient-290edd36-584d-4eb9-b155-48b899711cf4-eth0.lease -pf /var/run/dhclient-eth0.pid eth0
 /usr/sbin/rsyslogd -n
 /usr/bin/python -Es /usr/sbin/tuned -l -P
 /usr/sbin/sshd -D
 kworker/:
 /usr/libexec/postfix/master -w
 kworker/:1H
 -bash
 kworker/:1H
 kworker/:1H
 sshd: root@pts/
 -bash
 kworker/:1H
 kworker/:1H
 kworker/:
 kworker/:
 kworker/:
 kworker/:
 kworker/:
 sleep 

找出满足条件的最新/最老的一个进程（或线程）

比如root用户，他可能启动了很多进程（或线程），那么最近最新的是哪一个，使用-n(new)参数

[root@localhost lib]# pgrep -u root -a -n
 sleep 

如果找最老的那个进程（或线程），使用-o(old)参数（这个不是initd就是systemd）

[root@localhost lib]# pgrep -u root -a -o
 /usr/lib/systemd/systemd --switched-root --system --deserialize 

统计满足条件进程（线程）的个数

使用参数-c

pstree的-c是展开折叠

[root@localhost lib]# pgrep -u root  -c